Costanzo Bellini

• Mechanical Engineering
• PhD Student at University of Cassino and Southern Lazio

In recent years, there has been a growing interest in recyclable and eco-friendly materials, driven by the need to develop components with complex geometries, variable thicknesses, and large dimensions, particularly in sectors such as building and automotive. Eco-Sustainable Sandwich Panels (ESSP), which combine lightweight cores with thermoplastic...

Lattice structures are very interesting since they present good mechanical properties coupled with lightness. Today, the maturity reached by additive manufacturing technologies allows the production of such structures. However, the mechanical properties of the constituting material can be affected by the process itself, because of the particular ge...

Adopting novel sandwich structures with FRP (Fibre Reinforced Polymer) skins and a metallic lattice core, both of which have high specific strength and stiffness, is one way to achieve better mechanical performance while remaining lightweight. Flexural stress is a load pattern that frequently occurs in the structural frame components of automobiles...

Metal powders are used as the feedstock material during the Electron Beam Melting processes. The process involves using an electron beam as the energy source to produce intricate parts with complex shapes in a layer-by-layer production system. The electron beam is directed by information from an STL file, and the process takes place in a pre-heated...

Powder Bed Fusion (PBF) is part of the category of additive manufacturing processes and includes Electron Beam Melting (EBM). Metal powder that has previously been atomized is the raw material used in all EBM processes. Reusing surplus powder after its production cycle lowers manufacturing costs and improves productivity. Depending on how many time...

The electron beam powder bed fusion (PBF-EB) process has several advantages typical of additive manufacturing. However, at the end of the process, a large amount of powder is left that needs to be disposed of. Therefore, reusing powder for several build jobs may represent an interesting opportunity in the context of sustainable manufacturing. On th...

Within the powder bed fusion electron beam (PBF-EB) category, due to the high cost of material feedstock, the unused powder can be reused in subsequent production cycles, thereby reducing the costs associated with powder production. However, since the impact of recycling processes on the metallurgical and mechanical properties has not been fully in...

Brake pad linings are an essential part of the correct functioning of braking systems based on the use of pads and discs. Generally, the compounds used to make the gaskets are characterised by the use of over 20 sintered components, which allow friction coefficients that vary between 0.2 and 0.6 at temperatures up to 200 °C. In this work, a traditi...

Three key qualities should define the structures used in the aviation industry: they should be light, rigid, and strong. These goals can be met by selecting lightweight, high-performance materials like titanium alloy or composites, but careful structural design is also crucial to improve mechanical performance. The structures known as isogrids, whi...

In this paper, the abrasion resistance of a carbon fiber composite based on epoxy nanocomposite matrix filled with layered‐silicate clay nanoparticles was evaluated. In the first step of the work, the clay‐epoxy nanocomposite was first studied to assess the dispersion and the performance, and then to select the best content for the fiber composite...

In addition to a brief overview of powder bed fusion (PBF) process, which is a subcategory of additive manufacturing (AM) technology, various types of AM defects are thoroughly examined in this chapter, as well as their formation mechanisms during the AM process. Porosities, rough surfaces, and thermally generated micro-cracks are examples of defec...

Lattice structures made of metal materials are very interesting since their structural efficiency is elevated, thanks to their good mechanical properties and light weight. Additive manufacturing processes are appropriate to produce those structures. However, the peculiar geometry of lattice structures causes the manufacturing process to create rath...

Fibre Metal Laminates (FMLs) are very interesting materials due to their light weight coupled with their high stiffness, high fatigue resistance, and high damage tolerance. However, the presence of the polymeric matrix in the composite layers and of polymeric adhesive at the metal/composite interface can constitute an Achille’s heel for this class...

The Smart Landing Gear system to be developed in the framework of the ANGELA project provides the strain measurements on landing gear structure at landings, and this system should be maintained efficiently under operational conditions. It is intended to assess the relevance of Fiber Bragg Gratings for in-flight testing. To assess the capabilities o...

Metal lattice structures manufactured utilising additive techniques are attracting increasing attention thanks to the high structural efficiency they can offer. Although many studies exist on the characterisation of massive parts in Ti6Al4V processed by Electron Beam Melting (EBM), several investigations are necessary to characterise the Ti6Al4V la...

Abstracts Book - The 27th International Conference on Fracture and Structural Integrity February 21-24, 2023

Additive manufacturing (AM) techniques offer significant advantages with respect to conventional manufacturing (CM) ones such as the realization of highly customized components both dealing with their geometry and their mechanical properties. An important advantage of AM is the significant reduction of wasted material with respect to CM. However, A...

Hot dip galvanizing is among the cheapest methods for protecting ferrous alloys against corrosion. The success is due to both the low cost of the process and the high degree of protection in many corrosive environments, where the coatings serve as sacrificial protection. The purpose of this analysis is to study the mechanical characteristics of ste...

The core of the present work concerns the analysis of the failure mode and the fracture process induced by the flexural load in Fibre Metal Laminates (FMLs). The influence of the connection layer placed between the composite ones and the metal sheets on the fracture mode was analysed. The considered FML was made of aluminium sheets interposed with...

Electron Beam Melting is an additive manufacturing process that allows the creation of high-resolution parts with complex shapes, starting from a powder feedstock and using an electron beam as the energy input. Due to the high costs of the powder, the excess one must be reused otherwise a high percentage of unused powder would be lost after the pri...

Shape memory alloys are more and more used in many industrial, medical and automotive fields due to the ability to recover the initial shape after external loads producing high deformations thanks to the variations of their microstructure due to thermal or mechanical causes. Up to now, many models have been developed in order to describe the mechan...

Lattice structures represent a valuable solution for applications demanding both high mechanical properties and lightweight. However, the skin is required to obtain uniformity of the load distribution and avoid stress concentration. The characteristics of the skin materials can influence the mechanical properties of the structure; therefore, in the...

Fibre metal laminates represent a family of hybrid laminates with interesting mechanical properties, due to their lightness. Flexural loads are very frequent in structural parts; therefore, the investigation of the failure mode and the fracture behaviour connected to this loading state is crucial, and it constitutes the core of the present work, in...

The aim of this work is the analysis of the hot dip zinc coated steel plates mechanical properties by means of a traditional four-point bending test, performed on coated specimens at three different bending angles. Results are analysed both in terms of mechanical behaviour and phase damages of coatings. The influence of the chemical composition of...

Metal lattice structures produced by means of additive techniques are attracting increasing attention thanks to the high structural efficiency they can offer. In order to achieve the maximum structural performance, numerical design techniques are used almost exclusively, thus based on CAE-FEM codes. Nevertheless, the current manufacturing facilitie...

The employment of hybrid materials is frequently a solution for applications demanding high structural performances. FMLs (Fibre Metal Laminates) represent a group of hybrid materials, composed of metal sheets and composite material layers, and they exhibit good mechanical properties due to the presence of both types of material. The aim of this ar...

Shape memory alloys (SMA) are often used in many industrial, medical and automotive fields due to the ability to recover the initial shape caused by external loads. This aspect is due to the variations of the microstructure that may depend on thermal and/or mechanical causes. So far, many models have been developed in order to describe the mechanic...

High performances in terms of mechanical properties and lightweight are increasingly required to materials, and a solution to meet these requirements is the adoption of innovative hybrid structures made of metallic lattice core and composite material skins. In this work, two different processes are analysed and compared: co-curing and bonding. In t...

Shape memory alloys are able to recover the initial shape even after a large deformation. The memory property is due to the ability to change the microstructure under a variation of the stress state or the temperature. The stress–strain curve is characterized by the presence of a stage where the slope of the curve sharply decreases and the initial...

Lattice structures are very interesting for applications in the aerospace field since they combine high stiffness with lightweight. Moreover, they can constitute the core material for sandwich structures. In this work, the bending properties of two kinds of sandwich structures were compared through experimental activity: both of them had a lattice...

Additive manufacturing (AM) technologies are appreciated all over the world for their great versatility, including the possibility to realize very complex shapes in one step, increasing the design freedom and significantly lowering the production costs. There are different AM processes and the criterion used to classify them is not unique; however,...

Shape memory alloys are more and more used in many fields of mechanics and medicine. The reason of the success is the ability to recover the initial shape also after high values of deformation. During the deformation, the SMA are able to change the structure from an initial structure, often named as austenite, to a final structure named martensite....

The realization of hybrid materials allows to achieve high mechanical performances; for this reason, FMLs (Fibre Metal Laminates), which are the combination of composite material and sheet metal, have been used for several applications in different fields, such as aeronautic, aerospace, and automotive. In fact, the best characteristics of both cons...

Lattice structures allow achieving high stiffness and strength, maintaining the part weight low. There exist different technologies for the manufacturing of such structures, but the one having high flexibility and offering the possibility of producing parts with complex geometries is the additive manufacturing process. In this paper, titanium speci...

The structures adopted in the aeronautic field should have three main characteristics: they must be strong, stiff, and light. These targets can be obtained by choosing high performance and low weight materials, as composite or titanium alloy, but also the wise design of the structure itself is important for enhancing the mechanical performances. Th...

Lattice structures are characterized by good mechanical efficiency because their particular geometry confers high strength and stiffness coupled to lightweight. These structures can be produced using a wide range of technologies, but the additive manufacturing ones are the most promising. In this work, the flexural properties of titanium alloy latt...

High levels of stiffness, strength, and lightweight can be achieved through lattice structures. Many different technologies can be adopted for their construction; among them, additive manufacturing presents high flexibility and the capacity to produce complex shape parts. In this paper, a detailed analysis of the fracture surface was carried out on...

The thermomechanical interactions between the different materials constituting a hybrid laminate make residual stresses arise during the manufacturing process of such laminate. In turn, the residual stresses make the laminate deform as it is extracted from the mould. Cure induced deformation represent a problem for the assembly step, since addition...

The paper presents an innovative approach for the damage assessment of ductile cast irons (DCIs) by using a probabilistic-based methodology. The study is based on the experimental results of acoustic emissions (AEs) tests performed on pearlitic DCIs subjected to both monotonic and fatigue tensile loading. The information entropy of the AEs data is...

The paper presents the preliminary results of Acoustic Emission (AE) tests on a peralitic ductile cast iron (DCI) subjected to fatigue tensile loading. The focus is on the evaluation of the information Entropy of the AE data, as an innovative tool for a reliable assessment of fatigue damage in DCIs. Two damage indexes are proposed for the identific...

The damaging micromechanisms in a pearlitic (EN‐GJS700‐2) ductile cast iron (DCI) are investigated by means of scanning electron microscope (SEM) analysis and acoustic emission (AE) testing. Monotonic uniaxial tensile tests are performed on microtensile specimens under strain control. SEM analysis is applied under in situ conditions by means of a t...

The goal of this work is to analyze the damage evolution at microstructural scale of an austempered ductile iron partially austenized during tensile loading. The analysis is carried out by means of step‐by‐step tensile tests and the specimen's surface observation with optical and scanning electron microscopy. The results show that cracks initiate a...

The paper shows the preliminary results of uniaxial tension tests on a pearlitic Ductile Cast Iron (DCI) by using the Acoustic Emission (AE) technique as well as the Scanning Electron Microscope (SEM) analysis. The experimental tests demonstrate the damage initiation and evolution occurring within the graphite nodules produce AE activity. The evalu...

GLARE (Glass Laminate Aluminum Reinforced Epoxy) is a hybrid material composed of aluminum sheets alternated to fibre glass composite material and it is used for some applications in the aeronautical field. In the present work, the mechanical performance of a GLARE laminate is compared to that one of a GFRP (Glass Fibre Reinforced Polymer) laminate...

A Fibre metal laminate (FML) consists of a stack of metal sheets alternating to composite material layers: in such a manner, the best characteristics of both constituents are combined together. In this work, the flexural behaviour of different kinds of FMLs was investigated. In particular, both long beam and short beam specimens were produced and t...

A previous study concerning the characterization of CuNiSi (C70250) and CuCrZr alloys showed very interesting characteristics of toughness evaluated with tensile tests and preliminary tests on Charpy specimens. These alloys could have interesting applications such as devices used for energy production, particle physics and aerospace. These alloys a...

Shape memory alloys (SMAs) are more and more used in many fields of mechanics and medicine. The reason for the success is the ability to recover the initial shape also after high values of deformation. During the deformation, the SMAs are able to change the structure from an initial one, often named as austenite, to a final one, named martensite. T...

Lattice structures are very light and strong, but they need to be wrapped with skin to evenly distribute the loads over the entire surface of the structure. Considering additive manufacturing as a process to produce lattice structures, the easiest way to add the skin is its building together with the lattice core. However, if the core is made of me...

The goal of this work is to improve the understanding of the relation between the microstructural characteristics of Intercritical Austempered Ductile Cast Iron (IADI) and the damage micromechanisms observed during its tensile loading. The experimental methodology involves heat treatments to obtain IADI and the assessment of the damage mechanisms (...

FML (Fibre Metal Laminate) is a hybrid material that presents outstanding structural properties, such as resistance to cyclic and dynamic loads, together with low specific weight. This material consists of metal sheets alternating to composite material layers. In the present work, the ILSS (Interlaminar Shear Strength) was evaluated for different t...

Fibre metal laminates (FMLs) are a class of hybrid laminates made of composite material plies and metal sheets; they are used for applications where extraordinary mechanical properties are needed, due to their high damage tolerance, low weight, and high strength. In the present work the behaviour of different types of aluminium‐carbon fibres FMLs w...

A previous study concerning the characterization of a CuCrZr alloy, considered as a possible candidate for the construction of passive satellites while highlighting some critical issues such as low hardness and elastic modulus, showed very interesting characteristics of toughness evaluated with preliminary tests on Charpy specimens and tensile test...

FMLs (fibre metal laminates) are a kind of hybrid material consisting of composite material layers alternating to metal sheets, that present high mechanical characteristics. The aim of the present work deals with the flexural behaviour of CARALL (carbon fibre-reinforced aluminium laminates) specimens; in fact, the influence of both the layer thickn...

In the last decades, structural adhesives have found an increasing use owing to the fact that they, compared to traditional techniques like bolting and riveting, allow more uniform stress in the joint without drilling the parts of the assembly. Moreover, the quality of a bonded joint is strongly linked to the surface treatment used for the adherend...

In the last decades, the combination of high mechanical performances and low production costs increased the industrial interest on ductile cast irons. These grades are often used for applications where the fatigue resistance can be a critical issue (eg, machine frames for the wind‐power industry or crankshaft used in trucks) and the investigation o...

Using a finite element calculation code, this work analyses the influence of friction during a stamping test conducted on the AA6060 aluminium-based alloy. The study focuses on phenomena happening when the sheet necking appears. This condition, based on the Hill�s localized necking theory and the Swift�s diffuse necking theory, is dependent on the...

Industry needs new materials that present very high structural characteristic, such as high strength, low weight and high damage tolerance. To obtain these characteristics a new class of materials has been introduced: Fibre Metal Laminate (FML); they consist in metal sheets alternated to composite material layers: in such manner, the good character...

Ductile cast irons offer an interesting combination of good castability and high mechanical properties, with acceptable costs. This is due to the peculiar graphite nodules shapes obtained not by means of long and expensive heat treatments but by means of the chemical composition control. The relevant mechanical properties of these grades in the as...

In recent decades, designers have increasingly focused on the stability of assemblies in composite materials over time, particularly when used in structural applications. The use of structural adhesives allows for realising assemblies without mechanical fasteners. In fact, bonding is an assembly technique that prevent corrosion, ensures uniform str...

The robotic filament winding (RFW) technology consists of an industrial robot that is equipped with a feed and deposition systems; they are suitable for placing a tape along the stress directions the part is subjected to during operation. RFW cell replaces the human operator that is the only system that has been previously used to manufacture compl...

A new class of material characterized by mechanical properties close to the traditional low and medium carbon steel is the Ductile Cast Irons (DCIs). High castability and low production costs allow them to be used in many fields, ranging from automotive to piping. In this class of iron-based alloy the content of carbon is mainly localized in the gr...

Fibre metal laminate (FML) is a material constituted by composite laminae and metal sheets, whose mechanical properties can be tailored by varying the thickness and the number of layers. For this reason, in the present work different types of FML made of carbon fibre reinforced polymer and aluminium sheets were produced and tested; in particular, t...

The interest on the DCIs damaging mechanisms strongly increased, and the research activity was focused both the role played by the microstructure and on the influence of the graphite elements. In this work, the role played by the graphite elements during the fatigue crack propagation has been investigated by means of the analysis of the fatigue cra...

Cheaper metallic materials are susceptible to environmental corrosion due to low values of electrochemical potentials. For instance, low carbon steels, but recently ductile cast irons too, show many problems of mechanical properties degradation due to corrosion. Therefore, it is important to protect these alloys against corrosion for safety reasons...

Duplex Stainless Steels (DSSs) are an attractive class of materials characterized by a strong corrosion resistance in many aggressive environments. Thanks to the high mechanical performances, DSSs are widely used for many applications in petrochemical industry, chemical and nuclear plants, marine environment, desalination etc. Among the DSSs critic...

Cheap iron-based alloys, such as Ductile Cast Irons (DCIs) and low carbon steels, are more and more used in the mechanical field because they are characterized by good strength and good workability. However, the low value of electrochemical potential of low carbon steel leads to quick environmental corrosion that can compromise the operative life o...

Shape memory alloys (SMAs) are a wide class of materials characterized by the property to recover the initial shape also after high values of deformations. This is due to the ability of SMAs to change, in a reversible manner, their microstructure from an initial structure, often named austenite, to a final structure, named martensite. The transform...

Very high mechanical properties, such as high strength, high damage tolerance and low weight, can be reached by coupling composite laminae and metal sheets: in such a manner a new material is obtained: the Fibre Metal Laminate (FML). The diversification of the thickness and the number of layers is suitable to change the structural properties. In or...

High mechanical characteristics, such as impact and fatigue resistance, coupled with low weight can be obtained combining metal sheets and composite laminates; in this way a new hybrid material is obtained: the FML (Fibre Metal Laminate). In the present paper, an analysis of the influence of both composite/metal interface and layer thickness on ILS...

Nowadays composite materials play a leading role in structural design, particularly in aeronautics and automotive. In these industries, to reduce the weight of the components maintaining the same performance is most required. With this in mind, the use of structural adhesives allows to maximize the specific strength of assembled parts. To have a th...

Natural stone is a material that presents durableness over time and high aesthetic characteristic, but it is brittle and its tensile strength is significantly lower than compressive one: these peculiarities must be taken into account for material usage; in fact, for applications requiring high flexural and tensile strength, as thin sections or long...

Lightening parts, maintaining also a high strength, is a request of the transport industry. Isogrid structures represent one of the best answer to face these issues, especially if composite materials are considered for their production. However, the fabrication of these structures is very complex, as defects can arise that cause the part discarding...

This article addresses the optimization of curing process for thick composite laminates. The proposed methodology aims at the evaluation of the thermal cycle promoting a desired evolution of the degree of cure inside the material. At the same time, temperature overshooting as well as excessive temperature and cure degree gradient through the thickn...

During the cure process, the anisotropic characteristics of composite material, combined with high temperature and high pressure to which the material is subjected, cause the development of residual stresses. Consequently, laminate deformations arise and dimensional and geometrical requirements are not reached. Laminate deformations transfer into p...

This work analyses the results of a simple forming process of an AA6060 aluminum alloy sheet in order to validate the development of a simulation model based on the finite element method (FEM). This work represents the starting point of a broader study aimed at analyzing the sheet formability. The FEM based model and the use of both the flow stress...

Nowadays adhesives are widely used in structural applications, in particular for assembly composite materials. In fact, this technique allows to obtain a more uniform load in the joint, to realize a joint with a higher specific strength and to avoid drilling parts as in the case of bolted joints. However, the mechanical properties of bonded parts o...

The phenomena that happen during the cure process of a composite material laminate are responsible for the rise of residual stresses and, consequently, for the deformation at the end of the manufacturing process. The most analyzed deformation is the spring-in, that represent the flange-to-flange angle deviance from the theoretical value. In this wo...

The thermochemical and the thermomechanical phenomena that happen during the cure process of a composite material laminate are responsible for the rise of residual stresses and, consequently, for the deformation at the end of the manufacturing process. In this work, the influence of some parameters, such as the laminate thickness, the stacking sequ...

Composite materials are increasingly being used in various field of engineering interest over recent decades. As an alternative to fastening, bonding is one of the most promising assembly techniques of composite materials since it allows a uniform distribution of forces, it has a greater ability to dampen vibration and it does not raise any problem...

Assembling of parts made of composite materials is often obtained by bolted or riveted joints. Therefore, drilling is one of the most common machining operation for composite laminates. However, this process causes some kinds of damage on the laminates, as delamination; the aim of this work is to reduce the delamination of the laminate. First of al...

During the cure process of CFRP laminates, some geometrical unconformities can arise, due to several thermomechanical and thermochemical phenomena that make residual stress rise. Among these unconformities, one of the most studied is the spring-in, that is the deviation of the flange-to-flange angle from the design value. In this work a numerical m...

Machining of carbon fibre reinforced polymers is an important step for the integration of advanced materials into engineering applications. Machining damage due to excessive cutting forces may cause the rejection of the composite components at the final stages of their production cycle. The cutting forces are related to the surface finish and tool...

Drilling is the most important machining operation applicable to polymeric composite materials since it is essential for mechanical coupling of parts. Drilling process provokes several issues, including localized thermal shock, caused by the presence of abrasive and extremely hard fibres and the low thermal conductivity of composite, which restrict...

Among machining operations applied to polymeric composite materials, drilling is the more important one due to the need to implement mechanical couplings, which in most cases are not yet possible using structural adhesives. Such process is very critical because not only it causes the interruption of the fibers continuity, but also it can generate l...

Stone are usually cut by diamond wire, that is frequently used to square stone blocks in marble companies and to pull blocks out of quarries. The diamond wire machines used for carrying out the former task are afflicted with a lot of technological troubles, such as poor surface finishing, low efficiency (in comparison with diamond wire machines use...

Aeronautical and aerospace industries require light and robust structures. This target can be achieved designing isogrid structures made of composite material. In fact, such structures present both lightness and structural resistance. However, some problems can arise during the manufacturing process of these structures. In the present work the RFW...

During the curing process, the exothermic cross-linking reaction inside epoxy resin-based composites causes overheating and, eventually, a thermal degradation of the matrix. Thick sectioned epoxy composites require an optimized curing cycle in order to minimize the temperature raise inside the composite. However, the recommended cycle for thin lami...

The machining of fibre reinforced composites is an important activity for optimal application of these advanced materials into engineering fields. During machining, any excessive cutting force has to be avoided in order to prevent any product reject in the last stages of production cycle. Therefore, the ability to predict the cutting forces is esse...