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Abstract

In this work is exploited the possibility to use two optical techniques and combining their measurements for the 3D characterization of different tyres with particular attention to the tyre's section. Electronic Speckle Pattern Interferometry (ESPI) and Laser Scanner (LS) based on principle of triangulation have been employed for investigating and studying the tyre's section and 3D shape respectively. As case studies two different racing tyres, Michelin S9H and Pirelli Diablo respectively, have been considered. The investigation has been focused at the aim to evaluate and measure the section's components in order to add to the 3D model obtained by Laser Scanning accurate information about the different layers along through the tyres sections. It is important to note that the assessment about the different layers along the section is a very difficult task to obtain by visual inspection or classical microscopy and even with the LS. Here we demonstrate that the different layers can be easily highlighted and identified by mean of the ESPI.

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... Gom Inspect v.7.5, Geomagic Qualify v.12, 3D Reshaper v.7.1, Rapidform XOV2, and Polyworks Inspector v.12 were compared to evaluate their performances. In recent times, Pagliarulo et al. (2017) [20] have combined the data from Electronic Speckle Pattern Interferometry (ESPI) with laser scanning data for 3D characterization of racing tyres sections. ...
... Gom Inspect v.7.5, Geomagic Qualify v.12, 3D Reshaper v.7.1, Rapidform XOV2, and Polyworks Inspector v.12 were compared to evaluate their performances. In recent times, Pagliarulo et al. (2017) [20] have combined the data from Electronic Speckle Pattern Interferometry (ESPI) with laser scanning data for 3D characterization of racing tyres sections. ...
... Additionally, three calibrated test parts (a sphere, cylinder, and gauge block) were utilized by Barbero and Ureta (2011) to compare the accuracy of five 3D scanners [18]. [20] have combined the data from Electronic Speckle Pattern Interferometry (ESPI) with laser scanning data for 3D characterization of racing tyres sections. A comparative evaluation of different systems is highly valuable when several options are available for a particular application. ...
Article
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The process of generating a computerized geometric model for an existing part is known as Reverse Engineering (RE). It is a very useful technique in product development and plays a significant role in automotive, aerospace, and medical industries. In fact, it has been getting remarkable attention in manufacturing industries owing to its advanced data acquisition technologies. The process of RE is based on two primary steps: data acquisition (also known as scanning) and data processing. To facilitate point data acquisition, a variety of scanning systems is available with different capabilities and limitations. Although the optical control of 3D scanners is fully developed, still several factors can affect the quality of the scanned data. As a result, the proper selection of scanning parameters, such as resolution, laser power, shutter time, etc., becomes very crucial. This kind of investigation can be very helpful and provide its users with guidelines to identify the appropriate factors. Moreover, it is worth noting that no single system is ideal in all applications. Accordingly, this work has compared two portable (handheld) systems based on laser scanning and white light optical scanning for automotive applications. A car door containing a free-form surface has been used to achieve the above-mentioned goal. The design of experiments has been employed to determine the effects of different scanning parameters and optimize them. The capabilities and limitations have been identified by comparing the two scanners in terms of accuracy, scanning time, triangle numbers, ease of use, and portability. Then, the relationships between the system capabilities and the application requirements have been established. The results revealed that the laser scanner performed better than the white light scanner in terms of accuracy, while the white light scanner performed better in terms of acquisition speed and triangle numbers.
... The common methods are divided into interferometric and imaging-based methods. Interferometric methods include electric speckle pattern interferometry (ESPI) [1][2][3][4], shear interferometry [5,6], and holographic interferometry [7][8][9], and these methods generally produce subwavelength accuracy. Adopting high-efficiency phase extraction methods, such as the temporal phase-shifting method [10,11], spatial carrier phase-shifting method [12,13], and Fourier transform method [14,15], nanometer accuracy can be achieved under laboratory conditions. ...
... In the four experiments, we adjusted the rotation angle to acquire different speckle patterns, and then displacement fields containing 100 calculated points at the focal plane were calculated by normal DIC algorithm. Mean displacement of each speckle pattern was eventually converted to the measured angle using Equation (4). The range of the rotation angle was 4'-20', and the step of rotation was set to be 2'. ...
... The vibration signal was passed through the signal generator, to the amplifier, and finally to the cantilever beam. To ensure that the speckle sizes were all around 5 pixels, the defocusing degree was determined using Equation (4), and then the exposure time was adjusted to ensure a low CMZ value to acquire a speckle pattern with a high quality. The size of the vibrating beam was 235 mm × 10 mm, as shown in Figure 18. ...
Article
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The laser speckle correlation method has found widespread application for obtaining information from vibrating objects. However, the resolution and accuracy of the laser speckle correlation method as they relate to the defocusing degree have not been analyzed sufficiently. Furthermore, the possible methods for speckle pattern quality assessment and enhancement have not been studied. In this study, the resolution and accuracy of the laser speckle correlation method are analyzed, and it is found that they are affected by the defocusing degree and speckle pattern quality, respectively. A new speckle pattern quality criterion combining the mean intensity gradient and frequency spectrum was proposed, called CMZ. The quality of the speckle pattern is higher when the CMZ is closer to zero. The proposed criterion was verified by simulated speckle patterns and real speckle patterns with different speckle sizes, densities, and gray contrasts. In the experimental setup stage, a suitable defocusing degree can be selected based on the resolution requirement and optimal speckle size, and other experimental parameters can be determined according to the CMZ criterion. Rotation and vibration experiments verified the effectiveness of the laser speckle correlation method and confirmed the reliability of the experiment preparation based on proposed CMZ criterion.
... The shearography method is best for composite material inspection and analysis of various composite parts (i.e., composite sandwich structures [27,28], composite pipes [29], wind turbine blades, aerospace and automotive structures including racing tires [30]). In aerospace technologies the most commonly used and preferred materials include polymer composites and sandwich core materials. ...
... In aerospace technologies the most commonly used and preferred materials include polymer composites and sandwich core materials. The main disadvantage of shearography is in The shearography method is best for composite material inspection and analysis of various composite parts (i.e., composite sandwich structures [27,28], composite pipes [29], wind turbine blades, aerospace and automotive structures including racing tires [30]). In aerospace technologies the most commonly used and preferred materials include polymer composites and sandwich core materials. ...
Article
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Material failure may occur in a variety of situations dependent on stress conditions, temperature, and internal or external load conditions. Many of the latest engineered materials combine several material types i.e., metals, carbon, glass, resins, adhesives, heterogeneous and nanomaterials (organic/inorganic) to produce multilayered, multifaceted structures that may fail in ductile, brittle, or both cases. Mechanical testing is a standard and basic component of any design and fabricating process. Mechanical testing also plays a vital role in maintaining cost-effectiveness in innovative advancement and predominance. Destructive tests include tensile testing, chemical analysis, hardness testing, fatigue testing, creep testing, shear testing, impact testing, stress rapture testing, fastener testing, residual stress measurement, and XRD. These tests can damage the molecular arrangement and even the microstructure of engineered materials. Nondestructive testing methods evaluate component/material/object quality without damaging the sample integrity. This review outlines advanced nondestructive techniques and explains predominantly used nondestructive techniques with respect to their applications, limitations, and advantages. The literature was further analyzed regarding experimental developments, data acquisition systems, and technologically upgraded accessory components. Additionally, the various combinations of methods applied for several types of material defects are reported. The ultimate goal of this review paper is to explain advanced nondestructive testing (NDT) techniques/tests, which are comprised of notable research work reporting evolved affordable systems with fast, precise, and repeatable systems with high accuracy for both experimental and data acquisition techniques. Furthermore, these advanced NDT approaches were assessed for their potential implementation at the industrial level for faster, more accurate, and secure operations.
... Interferometric techniques are based on the interference phenomenon and, in particular, on the so-called 'speckle'. Speckle -which gives its name to one of the most widely used techniques 15 , Electronic Speckle Pattern Interferometry (ESPI) -is a phenomenon based on the coherence of the light used (i.e. the laser), which when striking a rough surface, makes a random phase jump without losing its coherence. This generates an interference effect that can be constructive or destructive, resulting in images composed of dark and bright 'dots'. ...
Conference Paper
Leather is one of the most representative materials of the leading sectors of world markets, such as fashion and luxury, interior design, automotive, thanks to its excellent properties able to guarantee its high quality. Although material of natural origin, leather undergoes numerous substantial transformations during the production process, which, together with its anisotropy and with the increasing use of a wide range of novel sustainable tanning systems, sometimes makes some defects unpredictable. This work describes how some specific instrumental detection techniques are able to provide information regarding the possible causes of defects, also revealing the specific phase of the tanning process potentially responsible for the problem; particularly, the study emphasizes the effectiveness of techniques such as ATR-IR (Attenuated Total Reflection Infrared) Spectroscopy, Scanning Electron Microscope (SEM)-X-Ray Probe, Gas Chromatography-Mass Spectrometry (GC-MS), DSC/TGA (Differential Scanning Calorimetry/ Thermogravimetric Analysis) in identifying the causes of stains, chromatic or morphological alterations, cracks and detachment of the finishing. Furthermore, in order to guarantee increasingly predictive and non-invasive approaches, Non-Destructive Testing (NDT) systems have been considered for their use in the quality control of tanning productions, with particular reference to the use of optical Interferometric Techniques, laser based, such as the Electronic Speckle Pattern Interferometry (ESPI), and of Computer Vision techniques, based on the acquisition and processing of signals and images at different wavelengths, from visible to infrared. The possibility of using robotic systems specifically designed for the scanning of online products, through non-destructive and automated approaches, was also evaluated thanks to the increasingly widespread use of deep learning approaches, where these technological developments will certainly benefit the production chain to achieve ever higher standards of quality of leather products. Keywords: Leather Defects; Advanced Diagnostics; Non-Destructive Testing; Quality Control; Novel Detection Techniques; Automated Approaches; Robotic Systems; Deep Learning.
... The use of ESPI on soft engineering materials like rubber is quite challenging due to the high deforma- tions that occur during the mechanical test, which quickly accelerate the decorrelation of the carrier (i.e., the speckle field). As a result, very little research on this topic can be found [38,39] . Fig. 10 shows an example of the typical experimental data attainable by the ESPI: the correlation fringe patterns (upper row) and phase maps (lower row). ...
Article
We developed and optimized a custom dynamic Electronic Speckle Pattern Interferometer (d-ESPI) for measuring time-dependent three-dimensional (3D) surface displacements during inflation testing of ocular tissues. The 3D displacement field was resolved under dynamic loading conditions for a simplified test case of a rubber phantom and a real-world test case of the posterior sclera of a human eye. We present the optical layout and calibration procedure of the d-ESPI, and demonstrate how the displacement field can be accurately resolved for specimen deformation rates up to 6 μm/s.
... Speckle interferometry is customary tool for precise measurements in engineering [5][6][7] , displacement measurement, vibration analysis, nondestructive evaluation [8][9][10][11] and it can be applied to different materials, from metals to composites. In this work, the use of the Electronic Speckle Pattern Interferometry (ESPI) as tool to characterize a stainless steel keg, in combination with an "ad hoc " algorithm for fringes analysis developed to fit the geometrical characteristics of the kegs, has been tested with the aim to reduce the human operations and to make the process of identifying any leaks semiautomatic. ...
Article
Integrity assessment of kegs is necessary to preserve the quality of the content stored and, consequently, human health. Here we show that inspection optical technique based on ESPI can be adopted successfully for assessing fully integrity of stainless steel keg. In particular two kegs, the first pre-finished and the second with a known leak, are compared in order to test the possibility to employ ESPI as a non-destructive testing tool to quickly revealing the presence and to partially locate a leak in automatic way. The acquired speckle images have allowed measurements of deformations of the two kegs under a known pressure. We demonstrate that the anomaly into the fringes dynamic pattern and the corresponding phase-contrast maps clearly reveal the presence of imperfections in the welding processes. We propose different algorithms customized to automate the process of leak recognition, localization and quantification thus validating ESPI system, for the first time in our knowledge, to test the quality of the production of steel kegs through a very fast process. In particular the proposed fringes analysis is completely new and it has been designed specifically for the kegs characteristics. We think this procedure could be utilized for industrial applications with the aim to improve quality and reduce costs.
... Phase recovery from LWIR holograms can be obtained with the same numerical procedure. Here, we focused on visible light holograms since the NDT based on a visible laser source is widely used in industrial applications [28][29][30]. Similar to standard shearography, the proposed setup has the advantages of being compact, portable, and tolerant to vibrations. ...
Article
Recent advances in digital holography in the far‐infrared region of the spectrum have demonstrated the potential use of digital holography in homeland security as a tool to observe hostile environments in which smoke, flames, and dust impair vision. However, to make this application practical, it is necessary to simplify the optical setup. Here, we show an off‐axis, self‐reference scheme that spills the reference beam out from the object beam itself and avoids the need for a complex interferometric arrangement. We demonstrate that this scheme allows the reconstruction of high‐quality holograms of objects captured under visible as well as far‐infrared light exposure. This could pave the way to the industrialization of holographic systems to enable users to see through fire. Moreover, the quantitative nature of the holographic signal is preserved. Thus, the reported results demonstrate the possibility to use this setup for optical metrology.
... The calculation of phase-contrast map is obtained by using well-known numerical processing, consisting into demodulation of the fringe pattern image, which provides a wrapped phase image, and the subsequent unwrapping step. 24 ...
Article
This paper aims to investigate the ability of ultrasonic and electronic speckle pattern interferometry to analyse the low-velocity impact internal damage mechanisms on basalt composite laminates and to provide information on the shape and the extent of the delamination in non-destructive way. Basalt/epoxy composites with different thicknesses have been realised and characterised by mechanical tests to investigate both fibre-dominated (tensile and flexural behaviour) and matrix-dominated properties (interlaminar shear strength). Specimens were impacted at penetration and at increasing energy values, to explore the damage onset and propagation. The results showed that the damage was concentrated under the impactor–material contact point and that the composite with intermediate thickness had the best balance between the different kinds of impact damages: delamination and indentation. Further, a good agreement was found between the overall data obtained by the two non-destructive techniques, confirming the capability of both techniques to examine the composite impact damage.
... ese techniques were previously known as rapid prototyping techniques, thanks to the possibility of manufacturing objects avoiding the employment of molds or other forming tools, thus enabling to reduce considerably the designing time and costs of the objects [1]. Furthermore, AM techniques in combination with reverse engineering [2][3][4] allow the development of customized devices. e main application fields of these technologies are related to development of mold inserts, biomedical devices (i.e., prostheses and scaffolds), machine components, and other components for different engineering sectors. ...
... AM importance in the reverse engineering method makes it more attractive. Researchers are using the acquired medical images to print the required designs for this purpose [11]. Moreover, within the medical technology additive manufacturing (AM) of titanium alloys using selective laser melting (SLM) has been broadly introduced for the construction of stiff, lightweight, and strong implants for orthopedic applications instead of conventional processes [12], allowing instant design, fabrication, and application according to our requirements [13]. ...
Article
Novel metamaterial unit cells with tunable strain were incorporated into titanium intramedullary (IM) nails to overcome problems of dense metallic implants. Three-dimensional (3D) models of cylindrical, pillar, and reference metamaterials were tuned and analyzed for structural authentication. Further, one solid IM nail (S0) and four different cylindrical metamaterial cell IM nails with gap sizes of 0.15 mm, 0.30 mm, 0.45 mm, and 0.60 mm were used to achieve 5% (S1), 10% (S2), 15% (S3), and 20% (S4) strain, respectively, in a 3-mm fracture, to investigate the healing outcomes. The bending stiffness (callus quality) in the S2 metamaterial IM nail increased by 22% between the 7th and 16th iterations, whereas for the S0, S1, S3, and S4 IM nails, the increases were 5.6%, 8.1%, 12.4%, and 9.0%, respectively. The S2 IM nail exhibited the best healing and bending stiffness; however, the S0 IM nail exhibited the worst results. This unique design was customized for different fracture gap sizes according to patient-specific needs.
... Nevertheless, the obtained findings confirmed a strong influence of the lay-down pattern and, hence, of the pore geometry on the viability/proliferation of the AMSCs seeded and cultured on the PCL scaffolds. In the literature, many studies frequently report the important roles of reverse engineering [30]- [33], computer-aided design (CAD), and finite element analysis [34]- [37], as well as the advances in methodologies of analysis and design strategies to develop smart devices for different applications [38]- [41]. ...
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It has been widely reported that breast reconstruction improves the quality of life of women who undergo mastectomy for breast cancer. This approach provides many psychological advantages. Today, different techniques are available for the breast oncoplastic surgeon that involve the use of breast implants and autologous tissues, also offering interesting results in terms of aesthetic and patient-reported outcomes. On the other hand, advanced technologies and design strategies (i.e. design for additive manufacturing, reverse engineering) may allow the development of customised porous structures with tailored morphological, mechanical, biological, and mass transport properties. For this reason, the current study deals with the challenges, principles, and methods of developing 3D additive manufactured structures in breast reconstructive surgery. Specifically, the aim was to design 3D additive manufactured poly(ε-caprolactone) scaffolds with different architectures (i.e. lay-down patterns). Preliminary mechanical and biological analyses have shown the effect of the lay- down pattern on the performances of the manufactured structures.
... Recent literature stresses the important role of reverse engineering [36]- [39], computer-aided design (CAD), and finite element analysis [40]- [43], as well as the potential of pushing the research toward the development of design strategies and methodologies of analysis in different fields of application [44]- [47]. ...
Article
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p align="left">Recently, a variety of craniofacial approaches has been adopted to enter the skull base, among those, the endonasal endoscopic technique. An effective watertight thereafter: the reconstruction can be performed using different materials, both autologous and non-autologous, individually or combined in a multilayer fashion. The current study was focused on the development of new advanced devices and techniques, aiding in reducing postoperative CSF leak rate. Additive manufacturing allows the design of devices with tailored structural and functional features and, as well, injectable semi-IPNs and composites; therefore specific mechanical/rheological and injectability studies are valuable. Accordingly, we propose new additive-manufactured and injectable devices.</p
... ese techniques were previously known as rapid prototyping techniques, thanks to the possibility of manufacturing objects avoiding the employment of molds or other forming tools, thus enabling to reduce considerably the designing time and costs of the objects [1]. Furthermore, AM techniques in combination with reverse engineering [2][3][4] allow the development of customized devices. e main application fields of these technologies are related to development of mold inserts, biomedical devices (i.e., prostheses and scaffolds), machine components, and other components for different engineering sectors. ...
Article
Additive manufacturing technologies allow for the direct fabrication of 3D scaffolds with improved properties for tissue regeneration. In this scenario, design strategies and 3D fiber deposition technique are considered to develop advanced scaffolds with different lay‐down patterns, tailored mechanical and biological properties. 3D poly(ε‐caprolactone) scaffolds are manufactured and surface‐modified (i.e., aminolysis). The effect of surface modification on the mechanical and biological performances of the designed 3D scaffolds is assessed.
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The surface quality verification of mechanical components is an essential activity in many applications where surface performance plays an important role in the functional behaviour of the part. Although many of the verification techniques commonly employed are based on the use of contact roughness profilometers, there are some limitations related to the morphological filtering effect associated to the stylus tip radius, as well as the difficulty in using these type of styli to carry out on-machine surface verification. The use of non-contact digitizing techniques helps to overcome some of these drawbacks, although the verification of surface quality using these non-contact systems still requires the development of scanning and data processing procedures similar to those described in the international standards for contact probing techniques. This work analyses the use of a non-contact sensor, based on Conoscopic Holography and integrated in a 3-axis machining centre, applied to the verification of the surface roughness of parts machined by face and cylindrical milling processes. After the calibration of the integrated system, a high-frequency noise filtering procedure specifically designed for roughness verification is proposed. The results demonstrate the feasibility of the system for verifying surface roughness grades from N5 to N12 in the two milling processes. Finally, specific filtering recommendations for each roughness grade of both milling processes as well as a surface verification procedure are provided.
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Conference Paper
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Composite materials/structures are advancing in product efficiency, cost-effectiveness and the development of superior specific properties. There are increasing demands in their applications to load-carrying structures in aerospace, wind turbines, transportation, and medical equipment, etc. Thus robust and reliable non-destructive testing (NDT) of composites is essential to reduce safety concerns and maintenance costs. There have been various NDT methods built upon different principles for quality assurance during the whole lifecycle of a composite product. This paper reviews the most established NDT techniques for detection and evaluation of defects/damage evolution in composites. These include acoustic emission, ultrasonic testing, infrared thermography, terahertz testing, shearography, digital image correlation, as well as X-ray and neutron imaging. For each NDT technique, we cover a brief historical background, principles, standard practices, equipment and facilities used for composite research. We also compare and discuss their benefits and limitations, and further summarise their capabilities and applications to composite structures. Each NDT technique has its own potential and rarely achieves a full-scale diagnosis of structural integrity. Future development of NDT techniques for composites will be directed towards intelligent and automated inspection systems with high accuracy and efficient data processing capabilities.
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Chapter
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3D inspection process is getting more and more interest for manufacturing industries as it helps to carefully check the expected quality of the released products. Much more attention is oriented to optical devices able to quickly capture the whole shape of the product providing many useful information on the process variability and the deliverability of the key characteristics linked to the quality of the product/process. Although the optical control of 3D scanners is mature enough, many factors may influence the quality of the scanned data. These factors may be strictly related to internal elements to the acquisition device, such as scanner resolution and accuracy, and external to it, such as proper selection of scanning parameters, ambient lighting and characteristics of the object surface being scanned (e.g. surface colour, glossiness, roughness, shape), as well as the sensor-to-surface relative position. For the 3D laser-based scanners, the most common on the market, it would be of great industrial interest to study some scanning factors mainly affecting the quality of the 3D surface acquisitions and provide users with guidelines in order to correctly set them so to increase the massive usage of these systems in the product inspection activities. In this context, by using a commercial triangulation 3D laser scanner, the effects of some scanning factors that may affect the measurement process were analysed in the present paper. Working on a sheet metal test part, more complex than the ones commonly used in laboratory and documented in the literature, the scanner-to-object relative orientation and the ambient lighting, as well as an internal scanner parameter, were tested. Through a Design of Experiments (DoE) approach, and setting root mean square error (RMSE) as response function, the outcomes of the tests mainly pointed out that the scanner-to-object relative orientation as well as its position within the field of view of the measurement device are the key factors mostly influencing the accuracy of the measurement process.
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In the paper new structure elements have been developed and implemented in the already-existing TRT thermo-dynamic tyre model. The updated model aims to provide a complete tool to study and understand all the phenomena concerning the tyre in thermal transient conditions, since all the elements constituting its structure are finally modelled. The computational cost, connected to a more complex model to manage, was decreased by simplifying the mesh of the previous version of the model and, thus, by reducing the state vector length.
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We report on a method for recovering data from a simple portable Digital Speckle Pattern Interferometer, we used for monitoring structural behavior of a painting on wood, hanging on a wall, outside of laboratory conditions, without anti-vibration devices. In such a situation, fringes produced by the object displacements were affected by unpredictable distortions caused by environment vibrations. However, an sufficient number of suitable, i.e., undistorted or barely distorted, fringe patterns usable for processing was found. We performed multiple acquisitions at a frame rate as high as possible. The main task was picking out usable interferograms from large amount of frames. We developed a PC-based method based on jointly analysis of spectral content and fringe image sharpness as selection rules. The selected frames were utilized for off-line processing by using an approach based on Hilbert Transform and Phase Unwrapping via MAx-flow (PUMA) algorithm. We obtained a collection of displacement-maps, that allowed for evaluating the whole structure deformations, caused by environmental thermo-hygrometric fluctuations.
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In this work, the application of Electronic Speckle Pattern Interferometry (ESPI) is employed for inspecting composite materials subject to thermal load. The composite samples are of interest in the aerospace industry. Through real-time surface illumination by visible laser (i.e. 532 nm), the ESPI technique allows the non-contact, non-destructive, full frame and real time detection of micro-deformations, micro-cracks, residual stress and delamination. The evaluation of the effective delaminated area of damaged polymer/Carbon Nanotubes fiber reinforced composites after flexural tests is presented.
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In the paper a new physical tyre thermal model is presented. The model, called Thermo Racing Tyre (TRT) was developed in collaboration between the Department of Industrial Engineering of the University of Naples Federico II and a top ranking motorsport team. The model is three-dimensional and takes into account all the heat flows and the generative terms occurring in a tyre. The cooling to the track and to external air and the heat flows inside the system are modelled. Regarding the generative terms, in addition to the friction energy developed in the contact patch, the strain energy loss is evaluated. The model inputs come out from telemetry data, while its thermodynamic parameters come either from literature or from dedicated experimental tests. The model gives in output the temperature circumferential distribution in the different tyre layers (surface, bulk, inner liner), as well as all the heat flows. These information have been used also in interaction models in order to estimate local grip value.
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SUMMARY In this paper we derive a new dynamic friction force model for the longitudinal road/tire interaction for wheeled ground vehicles. The model is based on a dynamic friction model developed previously for contact-point friction problems, called the Lu- Gre model (7). By assuming a contact patch between the tire and the ground we develop a partial differential equation for the distribution of the friction force along the patch. An ordinary differential equation (the lumped model) for the friction force is developed based on the patch boundary conditions and the normal force distribution along the contact patch. This lumped model is derived to closely approximate the dis- tributed friction model. Contrary to common static friction/slip maps, it is shown that this new dynamic friction model is able to accurately capture the transient behaviour of the friction force observed during transitions between braking and acceleration. A velocity-dependent, steady-state expression of the friction force vs. the slip coefficient is also developed that allows easy tuning of the model parameters by comparison with steady-state experimental data. Experimental results validate the accuracy of the new tire friction model in predicting the friction force during transient vehicle motion. It is expected that this new model will be very helpful for tire friction modeling as well as for anti-lock braking (ABS) and traction control design.
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A new analytical–physical tyre model for which the paternity has to be ascribed to Professor Giuseppe Capone was developed at the Department of Mechanical Engineering for Energetics at Naples University ‘Federico II’ with the support of the Bridgestone Technical Centre Europe. The whole model allows to obtain the road–tyre interactions so it can be used in vehicle dynamic simulations. The model has been named Ph.An.Ty.M.H.A., acronym of ‘PHysical ANalytical TYre Model for Handling Analysis’ and it includes the normal, longitudinal and lateral tyre–road interaction. Considering that Ph.An.Ty.M.H.A. is an analytical ‘deductive’ model, it is necessary to develop it starting just from the normal interaction, described in this paper, and then the other ones will be described in future papers. In fact, the normal interaction, i.e. the relationship between the normal load and the normal deflection, influences the tangential (longitudinal plus lateral) one, which determines the vehicle handling behaviour. The parameters used in this model are physical and geometrical so they can be measured on the real tyre. This property allows to better understand the tyre–road interaction mechanism. The tyre behaviour is modelled by analytical expressions based on equilibrium conditions and geometrical relations. To reproduce the experimental normal interaction and the pressure distribution, once the tyre geometrical quantities are known, it is necessary to identify some parameters, related to the tyre structure, by a comparison with the experimental data. Moreover, the predictive ability of the whole model, combined with a vehicle model, is very careful in analysing the vehicle handling [J.C. Dixon, Tyres, Suspensions and Handling, Cambridge University Press, Cambridge, 1991].
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Book
The definitive book on tire mechanics by the acknowledged world expert. © 2012 Hans Pacejka Published by Elsevier Ltd All rights reserved.
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Conference Paper
The aim of this paper is to investigate the ability of two different interferometric NDT techniques to detect and evaluate barely visible impact damage on composite laminates. The interferometric techniques allow to investigate large and complex structures. Electronic Speckle Pattern Interferometry (ESPI) works through real-time surface illumination by visible laser (i.e. 532 nm) and the range and the accuracy are related to the wavelength. While the ESPI works with the “classic” holographic configuration, that is reference beam and object beam, the Shearography uses the object image itself as reference: two object images are overlapped creating a shear image. This makes the method much less sensitive to external vibrations and noise but with one difference, it measures the first derivative of the displacement. In this work, different specimens at different impact energies have been investigated by means of both methods. The delaminated areas have been estimated and compared.
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The research reported in this paper was aimed mainly to investigate the different NDE techniques on specimens made by a new process labeled as "pulsed infusion", very crucial for voids content under critical loading conditions. The impact load, in fact, is critical for composite laminates due to their anisotropy, in particular in extreme temperature conditions due to their brittleness. An additional and very relevant aim was to collect a large number of experimental results to supply useful information for the numerical models needed to simulate the dynamic behavior of composite laminates. At the aim to investigate the response under dynamic loads of laminates fabricated by a new vacuum assisted technology labeled as "pulsed infusion", rectangular carbon fiber composite specimens were subjected to low velocity impact tests. Experimental tests up to complete penetration and at different energy levels, were carried out by a modular falling weight tower. All the parameters related to the phenomenon, like penetration energy, maximum force and indentation depths, were used to validate existing semi-empirical and numerical models. The largely used ultra sound technique (US) was adopted to investigate the delamination together with the thermo graphic technique. The results of the measurements were compared with data obtained on the same specimens by holographic analysis (ESPI). One of the scope was to investigate the crucial internal impact damage and assess the ability of an unconventional ND system (ESPI) in giving right information about non-visual damage generated inside composite laminates subjected to dynamic loads. Moreover, some of the specimens were cut to allow the fractographic analysis. The efficiency of the above mentioned new fabrication technology was studied also comparing the results with measurements from literature on impacted autoclave cured laminates. By the comparison between the results, good agreements were found denoting the efficiency and the applicability of the new fabrication and the used NDE methods.
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The most powerful engine, the most sophisticated aerodynamic devices or the most complex control systems will not improve vehicle performances if the forces exchanged with the road are not optimized by proper employment and knowledge of tires. The vehicle interface with the ground is constituted by the sum of small surfaces, wide about as one of our palms, in which tire/road interaction forces are exchanged. From this it is clear to see how the optimization of tire behavior represents a key-factor in the definition of the best setup of the whole vehicle.Nowadays, people and companies playing a role in automotive sector are looking for the optimal solution to model and understand tire's behavior both in experimental and simulation environments. The studies carried out and the tool developed herein demonstrate a new approach in tire characterization and in vehicle simulation procedures. This enables the reproduction of the dynamic response of a tire through the use of specific track sessions, carried out with the aim to employ the vehicle as a moving lab.The final product, named TRICK tool (Tire/Road Interaction Characterization and Knowledge), comprises of a vehicle model which processes experimental signals acquired from vehicle CAN bus and from sideslip angle estimation additional instrumentation. The output of the tool is several extra "virtual telemetry" channels, based on the time history of the acquired signals and containing force and slip estimations, useful to provide tire interaction characteristics. TRICK results can be integrated with the physical models developed by the Vehicle Dynamics UniNa research group, providing a multitude of working solutions and constituting an ideal instrument for the prediction and the simulation of the real tire dynamics.
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The aim of this paper is to investigate the ability of different NDT techniques to detect and evaluate barely visible and non-visible impact damage on composite laminates. Firstly, a conventional ultrasound technique was adopted to investigate the delamination in carbon fibre laminates after low velocity impact s. Then the results were compared with a thermographic and holographic analysis, as well as a theoretical simulation of the expected delamination. The results were compared and discussed. Overall a good agreement was found between the data obtained by the different techniques. Furthermore, the true values of the damage parameters were confirmed by DT performed on the samples.
Conference Paper
The quality of 3D scanned data is influenced by many factors both related to internal elements to the acquisition device, such as scanner resolution and accuracy, and external to it, such as proper selection of scanning parameters, ambient illumination and characteristics of the object surface being scanned (e.g. surface colour, glossiness, roughness, shape). Due to the recent developments in terms of accuracy, in particular for 3D laser scanners, today it is of great industrial interest to study and correctly setting the scanning parameters that allow to improve the quality of the 3D acquisitions so to increase the massive usage of these systems in the product inspection activities. In this paper the effects of some scanning parameters that may affect the measurement process, were analysed by using a commercial triangulation 3D laser scanner. The test geometry chosen for this study was a commercial sheet metal part more complex than the ones commonly used in laboratory and documented in the literature. Relative orientation, ambient illumination and scanner parameters were tested. The outcomes of the tests confirmed some results and suggestions documented in literature but also pointed out that over different conditions the most influencing factor are the relative orientation of the object with respect to the scanner, as well as its position within the field of view of the measurement device.
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This study investigates, experimentally and analytically, the polygonal wear of truck/bus and car tires and elucidates the generation mechanism of polygonal wear caused by the first natural vibration mode of the tire in the vertical direction. In the analysis, the phenomenon is modelled as a time delay system accompanied by wear in which the amount of wear of the tire is fed back as forced displacement in the vertical direction after the time period of tire rotation. The progress of the polygonal wear of the tire is very slow and is caused by unstable vibration in the steady-state wear process generated in the limited regions where the products of polygonal numbers and the rotational speed of the tire are less than the natural frequencies of the tire system. The tire is deformed almost to the shape of a regular polygon when polygonal wear occurs. Good agreement between experimental and analytical results concerning the occurrence of polygonal wear of the tire was confirmed.
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This paper deals with the frictional behaviour of a tyre tread elementary volume in sliding contact with road asperities. Friction is supposed as composed by two main components: adhesion and deforming hysteresis. The target, fixed in collaboration with a motorsport racing team and with a tyre manufacturing company, is to provide an estimation of local grip for on-line analyses and real time simulations and to evaluate and predict adhesive and hysteretic frictional contributions arising at the interface between tyre tread and road. A way to approximate asperities, based on rugosimetric analyses on macro and micro scale, has been introduced. The adhesive component of friction has been estimated by means of a new approach based on two different models found in literature, whose parameters have been identified thanks to a wide experimental campaign previously carried out. The hysteretic component of friction has been estimated by means of an energy balance taking into account rubber viscoelastic behaviour, characterized by means of proper DMA tests, and internal stress / strain distribution due to indentation with road. Model results are finally shown and discussed and the validation experimental procedure is described. The correct reproduction of friction phenomenology and the model prediction capabilities are highlighted making particular reference to grip variability due to changes in working conditions.
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A Numerical–physical tyre model was developed . The whole model allows to obtain the road–tyre interactions so it can be used in vehicle dynamic simulations. In this article are presented its capabilities in normal interaction analysis. The normal interaction, i.e. the relationship between the normal load and the normal deflection, influences the tangential (longitudinal plus lateral) one, which determines the vehicle handling behaviour. The parameters used in this model depend on the structure of the tyre and they can be measured on the real tyre. The tyre has been schematized as composed by a flexible belt , the sidewalls and a rigid ring (Rim). The flexible belt is composed by a number of lumped masses linked by extensional and bending stiffnesses and dampers. The tyre model has been developed using the finite segment method. Using these method could be possible to include in the tyre simulations various non-linear structural effects due to large displacements and rotations. The model allows to simulate both steady state and transient conditions.
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Using Electronic Speckle Pattern Interferometry (ESPI), full-field displacement measurement was performed on the edge of a cracked cross-ply graphite/epoxy laminate subjected to a tensile loading. The displacement jumps corresponding to cracks are clearly visible and can be used to determine the crack opening displacement (COD) values along the cracks. The main objective of this study is to determine if the application of successive loads of increasing magnitude may have modified the existing cracks and thereby changed the COD dependence on the applied stress. Moreover, we have tested the applicability of the assumed linear elastic COD behavior in the presence of very high stress concentration at the crack tips. The profile of the opening along the crack was also studied.
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The fatigue behaviour of next generation high strength steels (σUTS=950–1000MPa) has been studied. Specifically, this study is focused on the initiation stage of fatigue microcracks. With this purpose, high cycle fatigue tests under uniaxial loading have been performed. During these tests, the deformation history of the specimen has been tracked by means of speckle interferometry. This technique allows monitoring the evolution of the displacement field and its derivatives on the specimen surface, so that it can be used as a tool for detecting microcracks in the first stages of crack initiation. The observation of the fracture surfaces provides complementary information about the localization of the initiation of failure thus, a correlation between the observations made by interferometry and the actual location of the fatigue nucleus and the evolution of the crack during its propagation can be established. Results appoint speckle interferometry as a promising technique for the detection of fatigue failures.
Article
We propose a denoising method for digital holography mod 2π wrapped phase map by using an adaptation of the SPArsity DEnoising of Digital Holograms (SPADEDH) algorithm. SPADEDH is a l<sub>1</sub> minimization algorithm able to suppress the noise components on digital holograms without any prior knowledge or estimation about the statistics of noise. We test our algorithm with either general numerical simulated wrapped phase, quantifying the performance with different efficiency parameters and comparing it with two popular denoising strategies, i.e., median and Gaussian filters, and specific experimental tests, by focusing our attention on long-sequence wrapped quantitative phase maps (QPMs) of in vitro cells, which aim to have uncorrupted QPMs. In addition, we prove that the proposed algorithm can be used as a helper for the typical local phase unwrapping algorithms.
Article
In this paper we propose a robust method to suppress the noise components in digital holography (DH), called SPADEDH (SPArsity DEnoising of Digital Holograms), that does not consider any prior knowledge or estimation about the statistics of the noise. In the full digital holographic process we must mainly deal with two kinds of noise. The first one is an additive uncorrelated noise that corrupts the observed irradiance, the other one is the multiplicative phase noise called speckle noise. We consider both lensless and microscope configurations and we prove that the proposed algorithm works efficiently in all considered cases suppressing the aforementioned noise components. In addition, for digital holograms recorded in lensless configuration, we show the improvement in a display test by using a Spatial Light Modulator (SLM).
Article
Due to their many economic and ecological implications the possibility to predict tyre wear is of major importance to tyre manufacturers, fleet owners and governments. Based on these observations, in 2000 a three-year project named Tyre and Road Wear and Slip assessment (TROWS) was started. One of the TROWS objectives was to provide a tool able to numerically predict tyre global wear as well as to qualitatively determine the wear distribution. The proposed methodology combines a mathematical model of the tyre with an experimentally determined local friction and wear law. Thus, tyre abrasion due to each single manoeuvre can be determined. Full-scale experimental tests were carried out with two Peugeot 406 cars on a public road course in Italy. Each car was equipped with a different set of tyres: one car was equipped with four all-season tyres (from now on called A tyres) and the other car was equipped with four winter tyres (from now on called B tyres). Both sets of tyres had a 195/65 R15 size. The collected data was used to validate the model. The methodology proved to give qualitatively good tyre wear predictions.
Article
The paper deals with the estimation of the pressure distribution, the shape of contact and the friction force at the interface of a flat soft elastic solid moving on a rigid half-space with a slightly wavy surface. In this case an unsymmetrical contact is considered and justified with the adhesion hysteresis. For soft solids as rubber and polymers the friction originates mainly from two different contributions: the internal friction due to the viscoelastic properties of the bulk and the adhesive processes at the interface of the two solids. In the paper the authors focus on the latter contribution to friction. It is known, indeed, that for soft solids, as rubber, the adhesion hysteresis is, at least qualitatively, related to friction: the larger the adhesion hysteresis the larger the friction. Several mechanisms may govern the adhesion hysteresis, such as the interdigitation process between the polymer chains, the local small-scale viscoelasticity or the local elastic instabilities. In the paper the authors propose a model to link, from the continuum mechanics point of view, the friction to the adhesion hysteresis. A simple one-length scale roughness model is considered having a sinusoidal profile. For partial contact conditions the detached zone is taken to be a mode I propagating crack. Due to the adhesion hysteresis, the crack is affected by two different values of the strain energy release rate at the advancing and receding edges respectively. As a result, an unsymmetrical contact and a friction force arise. Additionally, the stability of the equilibrium configurations is discussed and the adherence force for jumping out of contact and the critical load for snapping into full contact are estimated.
Conference Paper
Electronic Speckle Pattern Interferometry (ESPI) is a fast developing whole field optical technique used for the measurement of optical phase changes under object deformations and has evolved as a powerful on-line nondestructive evaluation (NDE) tool. In ESPI the speckle interferometry data of the object under different loading conditions are stored as digital images and then converted into interference fringes by digital subtraction or by addition method. These interference patterns correspond to surface displacements, which in turn relates to the strain variation in the specimen. Defects in the specimen produce a strain concentration on loading and generate a fringe anomaly in the interferogram. These anomalies in the interferogram are analyzed for the characterisation of defects in the material. This technique is used as an effective tool in Non-Destructive Evaluation (NDE). In this paper a method for on-line analysis of ESPI fringe patterns for the qualitative evaluation in the materials is presented. Continuous acquisition and simultaneous digital processing of specklegrams has been developed for generating the fringe patterns. The image acquisition and processing system used for the present study is an algorithm developed by using Imaging Graphs software. Image processing techniques are introduced for contrast enhancement, noise reduction and fringe sharpening for the on-line detection of different types of defects in the material.
Article
This paper presents a new algorithm for recovering the absolute phase from modulo-2π phase, the so-called phase unwrapping (PU) problem. PU arises as a key step in several imaging technologies, from which we emphasize interferometric SAR and SAS, where topography is inferred from absolute phase measurements between two (or more) antennas and the terrain itself. The adopted criterion is the minimization of the L p norm of phase differences [1], [2], usually leading to computationally demanding algorithms. Our approach follows the idea introduced in [3] of an iterative binary optimization scheme, the novelty being the casting onto a graph max-flow/min-cut formulation, for which there exists efficient algorithms. That graph formulation is based on recent energy minimization results via graph-cuts [4]. Accordingly, we term this new algorithm PUMF (for phase unwrapping max-flow). A set of experimental results illustrates the effectiveness of PUMF.
An evolved version of thermo racing tyre for real time applications In: Lecture notes in engineering and computer science-proceedings of the world congress on engineering 2015
  • F Farroni
  • A Sakhnevych
  • F Timpone
Farroni F, Sakhnevych A, Timpone F. An evolved version of thermo racing tyre for real time applications. In: Lecture notes in engineering and computer science-proceedings of the world congress on engineering 2015, London, UK, 1-3 July 2015, vol II; 2015. p. 1159-64.
The magic formula tyre model
  • H B Pacejka
  • E Bakker
Pacejka HB, Bakker E. The magic formula tyre model. In: Proceedings of the 1st international colloquium on tyre models for vehicle dynamics analysis. Amsterdam/Lisse: Swets & Zeitlinger BV; 1993.