Jaime Domínguez

Universidad de Sevilla | US · Mechanical Engineering and Materials

This paper investigates the dynamics of a Duffing oscillator excited by an unbalanced motor. The interaction between motor and vibrating system is considered as nonideal, which means that the excitation provided by the motor can be influenced by the vibrating response, as is the case in general for real systems. This constitutes an important differ...

Callus tissue exhibits a viscoelastic behavior that has a strong influence on the distribution of stresses and their evolution with time and, thus, it can affect tissue differentiation during distraction procedures. For this reason, a deep knowledge of that viscoelastic behavior can be very useful to improve current protocols of bone distraction an...

This study presents an experimental methodology aimed at estimating the residual fatigue life of in-service wind turbine bolts. The main objective is to assess the residual life of the bolts to plan their replacement and to avoid unexpected breakages of wind turbine blade connections. To develop the methodology, M16 bolts of quality 10.9 with contr...

Collagen is a ubiquitous protein present in regenerating bone tissues that experiences multiple biological phenomena during distraction osteogenesis until the deposition of phosphate crystals. This work combines fluorescence techniques and mathematical modeling to shed light on the mechano-structural processes behind the maturation and accommodatio...

Fretting fatigue is a material damage phenomenon produced in mechanical contacts. This phenomenon mainly produces surface cracking, and depending on the fretting regime, surface wear. In the bibliography many different types of fretting tests, with different geometries have been proposed. This paper numerically analyses, via FEM models, some fretti...

This chapter investigates the problem of an unbalanced motor attached to a fixed frame by means of a nonlinear spring and a linear damper. The proposed mathematical model is simple enough to allow for an analytical treatment of the equations, while sufficiently complex to preserve the main nonlinear phenomena that can be observed in real unbalanced...

In this article a new fretting fatigue life prediction model is presented. The model can be classified as a variable crack initiation length: the crack initiation and crack propagation phases are calculated as a function of the crack initiation length, and among all the feasible crack initiation lengths and orientations, that producing the minimum...

The rotating beam problem has been extensively used as a benchmark for testing nonlinear finite element implementations. The remarkable characteristic of this benchmark is the coupling between axial a transverse deformations due to the centrifugal forces. The rotating beam dynamics exhibits a centrifugal stiffening effect that can only be captured...

Additive manufacturing (AM) of metallic parts is a relatively new manufacturing procedure. Many industry sectors, such as the aerospace or automotive sectors, have started to apply this technology to produce some elements, thus reducing costs and weight. Several metallic alloys have been employed for AM. Due to the high strength-to-density ratio, T...

Shot peening (SP) is frequently used as a palliative measure against metal fatigue in many engineering components. The performance of this surface treatment depends on different factors including the material, shape and loading conditions of the component, as well as process parameters. Fatigue improvement due to SP depends to a great extent upon t...

Tissue engineering has recently gained popularity as an alternative to autografts to stimulate bone tissue regeneration through structures called scaffolds. Most of the in vivo experiments on long-bony defects use internally-stabilized generic scaffolds. Despite the wide variety of computational methods, a standardized protocol is required to optim...

A poloidal array of scintillator-based Fast-Ion Loss Detectors (FILDs) has been installed in the ASDEX Upgrade (AUG) tokamak. While all AUG FILD systems are mounted on reciprocating arms driven externally by servomotors, the reciprocating system of the FILD probe located just below the midplane is based on a magnetic coil that is energized in real-...

The increased availability of additively manufactured materials provides a new extended design freedom for innovative products and applications, especially with view to high-tech demands as in the aerospace industry. Current microstructural challenges relevant for fatigue life like internal processing defects and tensile macro stresses still requir...

In the present work a series of fatigue tests on Ti6Al4V SLM parts are analyzed via both SEM and confocal microscopy. On the one hand, fracture surfaces are studied, and a common pattern is found, formed by a series of different textures which show the complex crack front evolution from crack initiation in a particular internal defect to complete f...

Purpose The incipient growth of the fused deposition modeling (FDM) techniques encourages the development of models to predict the behavior of these parts involving complicated and heterogeneous geometries whose behavior strongly diverges from the continuous model hypothesis. This paper aims to address the problem of predicting the flexural propert...

Bone lengthening and bone transport are regeneration processes that commonly rely on distraction osteogenesis, a widely accepted surgical procedure to deal with numerous bony pathologies. Despite the extensive study in the literature of the influence of biomechanical factors, a lack of knowledge about their mechanobiological differences prevents a...

This paper aims at studying the influence of the different support types on the free nonlinear vibration frequency of a beam, both by analytical and numerical approaches and its dependence on the vibration amplitude. First, an analytical study of two cases of simply supported beams is carried out by using the nonlinear normal modes (NNM) and the mu...

Bone lengthening is a bone regeneration technique with multiple clinical applications. One of the most common complications of this treatment is the lack of adaptation of the surrounding soft tissue to their extension. A better understanding of the mechanobiology of the tissues involved in distraction osteogenesis would allow better control of the...

For the monitoring of bone regeneration processes, the instrumentation of the fixation is an increasingly common technique to indirectly measure the evolution of bone formation instead of ex vivo measurements or traditional in vivo techniques, such as X-ray or visual review. A versatile instrumented external fixator capable of adapting to multiple...

The data-driven approach was formally introduced in the field of computational mechanics just a few years ago, but it has gained increasing interest and application as disruptive technology in many other fields of physics and engineering. Although the fundamental bases of the method have been already settled, there are still many challenges to solv...

Different alloys can be used for Additive Manufacturing (AM) with good structural strength. Among the titanium alloys, Ti6Al4V is the most used, especially for aerospace applications. There have been many analyses of the mechanical properties of additive manufactured Ti-6Al-4V with very good static strength results in general. However, there are st...

The data-driven methodology with application to continuum mechanics relies in two main pillars, namely, (i) experimental characterization of stress-strain pairs associated to different loading states, and (ii) numerical development of the elasticity equations as an optimization (searching) algorithm using compatibility and equilibrium as constraint...

The woven bone created during the healing of bone regeneration processes is characterized as being extremely inhomogeneous and having a variable stiffness that increases with time. Therefore, it is important to study how the mechanical properties of woven bone are dependent on its microarchitecture and especially on its porosity and mineral content...

Multiscale analysis has become an attractive technique to predict the behaviour of materials whose microstructure strongly changes spatially or among samples, with that microstructure controlling the local constitutive behaviour. This is the case, for example, of most biological tissues—such as bone. Multiscale approaches not only allow, not only t...

Fretting fatigue is a surface damage phenomenon appearing in mechanical contacts subjected to time variable contact forces. Typical features of fretting fatigue include: wear, oxidation, high stress concentration and non-proportional loading. The high stresses near the surface produce a rapid initiation of cracks. Among the different fretting fatig...

High stress concentrations, slip and wear appear in shrink-fitted shafts near the contact edge in operational conditions. Due to these high stresses, and time fluctuation nature of the loads supported by shafts, cracks rapidly initiate at this surface location. This combination of events is known as fretting fatigue, which is a damage phenomenon pr...

Background: Breast cancer is the leading malignant tumor in women in the world. Reconstruction after mastectomy plays a key role in the physical and psychological recuperation, being the abdominal skin and adipose tissue the best current option for the DIEP surgery. The aim of the surgery is to obtain a reconstructed breast which looks and behaves...

The crack opening/closure load concept is widely used to justify the fatigue crack growth behaviour with different load ratios and the load interaction effects. Many experimental techniques have been proposed to measure crack opening/closure load, and amongst them, compliance offset methods are widely used for their simplicity and consistency. In t...

Fatigue failure of cables and strands is a common and complex problem. Failure is typically caused by different combinations of time‐variable bending and axial forces. In addition to these loads, contact stresses between wires may play an important role in the fatigue failure of cables. The present work aims to provide deep insight into the fatigue...

In silico models of distraction osteogenesis and fracture healing usually assume constant mechanical properties for the new bone tissue generated. In addition, these models do not always account for the porosity of the woven bone and its evolution. In this study, finite element analyses based on computed tomography (CT) are used to predict the stif...

Shot peening is a mechanical treatment that induces several changes in the material: surface roughness, increased hardness close to the surface, and, the most important, compressive residual stresses. This paper analyzes the effect of this treatment on alloy Al 7075-T651 in the case of fretting fatigue with cylindrical contact through the results o...

The fracture of cables is often caused by fatigue phenomena. To analyse the fatigue behaviour of these elements, a device has been designed, manufactured, and validated. This machine can produce different load states for the specimens, combining variable axial loads and variable bending moments. The testing machine has been designed to achieve two...

This work numerically analyses the initial crack path in a fretting fatigue situation. To this end, different criteria to estimate the crack growth (while the crack is less than 57μm) have been used. The analysis is performed using a 2D symmetric model of a cylindrical contact fretting problem, consisting of two cylindrical indenters, pressed onto...

A new reciprocating scintillator based fast-ion loss detector has been installed a few centimeters above the outer divertor of the ASDEX Upgrade tokamak and between two of its lower Edge Localized Modes (ELM) mitigation coils. The detector head containing the scintillator screen, Faraday cup, calibration lamp, and collimator systems are installed o...

Introduction: Bone transport appears to be a solution for segmental bone defects; specifically, the "docking site" is where the transported segment meets the target segment at the end of the process. A lack of its consolidation is one of the major causes of failure for this technique. Many studies have been performed in order to enhance the consol...

This volume is a collection of edited papers presented at the 17th International Conference on Fracture and Damage Mechanics (FDM 2018), held on 4-6 September 2018, Seville, Spain. The conference served as a forum to promote and exchange latest theoretical, computation and experimental research works on fracture, damage mechanics, structural integr...

Wear has been analyzed in several fretting fatigue tests with spherical contact performed on Al 7075 T651. The contact zone leaves a circular scar on the surface, which is easily detected because of the damage. Inside the contact zone, and almost concentric, another circular region called the stick zone can be distinguished. The annulus around it i...

Woven tissue is mainly present in the bone callus, formed very rapidly either after a fracture or in distraction processes. This high formation speed is probably responsible for its disorganized microstructure and this, in turn, for its low stiffness. Nonetheless, the singular volumetric composition of this tissue may also play a key role in its me...

This paper considers a kind of industrial process where a granular material is compacted by using vibration machines. In particular, attention is focused on the vibrocompaction of quartz agglomerates, where the vibration is produced by rotation of unbalanced electric motors. A four degree-of-freedom nonlinear model, which includes contact and impac...

Knowing the mechanical properties of human adipose tissue is key to simulate surgeries such as liposuction, mammoplasty and many plastic surgeries in which the subcutaneous fat is present. One of the most important surgeries, for its incidence, is the breast reconstruction surgery that follows a mastectomy. In this case, achieving a deformed shape...

There are several procedures used to increase fatigue life of components suffering from fretting, certain of which involve the modification of the surface material properties or the generation of compressive residual stresses near the surfaces in contact. Moreover, relatively little attention has been paid to the situation in which the contact pair...

Currently, additive manufacturing with metals is an increasingly popular technique that allows the manufacturing of pieces of difficult shapes, nearly impossible to make with other techniques. Usually, these shapes try to optimize the solid to have the same strength with a lower weight. The fatigue behavior of the material of the components manufac...

This paper focuses on the Nonlinear Normal Modes of simply supported beams with unrestrained axial displacements. Two different configurations are considered, depending on whether longitudinal displacements are allowed at one end of the beam or at both ends. An integro-differential equation is obtained for the transverse displacement of the beam, u...

This paper revisits the problem of an unbalanced motor attached to a fixed frame by means of a nonlinear spring and a linear damper. The excitation provided by the motor is, in general, nonideal, which means it is affected by the vibratory response. Since the system behaviour is highly dependent on the order of magnitude of the motor characteristic...

The simulation of long life behavior and environmental aging effects on composite materials are subjects of investigation for future aerospace applications (i.e. supersonic commercial aircrafts). Temperature variation in addition to matrix oxidation involves material degradation and loss of mechanical properties. Crack initiation and growth is the...

Nanoindentation has been used successfully in the determination of the mechanical properties of bone. Its application in fracture healing provides information on the evolution of material properties of the woven bone during regeneration process. However, this technique has not been applied in assessing the mechanical properties of woven bone during...

The correct characterisation of the articular disc of the temporomandibular joint (TMJ) is key to study the masticatory biomechanics. For the interval from extraction until testing, freezing is the most used preservation technique for biological tissues, but its influence on their behaviour is still unclear. An important error can be committed in t...

The correct characterisation of the articular disc of the temporomandibular joint (TMJ) is key to study the masticatory biomechanics. For the interval from extraction until testing, freezing is the most used preservation technique for biological tissues, but its influence on their behaviour is still unclear. An important error can be committed in t...

This study is the natural continuation of a previous paper of the authors González-Carbajal and Domínguez in J. Sound Vib. (Under revision), where the possibility of finding Hopf bifurcations in vibrating systems excited by a nonideal power source was addressed. Herein, some analytical tools are used to characterize these Hopf bifurcations, derivin...

The initial crack path is analysed in a series of fretting fatigue tests with cylindrical contact. In such tests, both specimens and pads are made of Al7075-T651 alloy and a non-proportional multiaxial stress state with a significant stress gradient is present. The crack initiation path along the fracture surface is optically measured using a focus...

A magnetically driven fast-ion loss detector system for the ASDEX Upgrade tokamak has been designed and will be presented here. The device is feedback controlled to adapt the detector head position to the heat load and physics requirements. Dynamic simulations have been performed taking into account effects such as friction, coil self-induction, an...

Introduction: Bone transport (BT) for segmentary bone defects is a well-known technique as it enables correction with new bone formation, which is similar to the previous bone. Despite the high number of experimental studies of distraction osteogenesis in bone lengthening, the types of ossification and histological changes that occur in the regene...

A system for controlling stability in heavy machinery of the type including chains or treads, based on risk of rollover associated with the working position thereof, having multiple detectors measuring the reaction value at the support points of the machine on the ground, determination in each instant of a support base defined by the actual support...

This paper analyses the initial crack path in a fretting fatigue test of Al7075-T651 alloy with a cylindrical contact and compares the capability of some multiaxial fatigue criteria to predict the crack initiation path. The experimental crack initiation paths obtained in the tests are optically measured along the fracture surface using a focus vari...

The initial crack path is analysed in a fretting fatigue test with cylindrical contact, where there is a stress gradient and a multiaxial and non-proportional stress state. For this, a cylindrical pad is pressed, with a constant normal load, N, against a dog-bone type fatigue test specimen. Then, the test specimen is subjected to a cyclic axial str...

Bone transport studies have measured the forces related to bone segment distraction (Brunner et al., 1994; Hyodo et al., 1996). However, no distraction force distribution between callus and docking-site was reported. Besides, most of these works have not provided continuous and long-term force relaxation measurements. The fit of the relaxation curv...

The use of composite materials is growing over nowadays, not only in the aerospace industry but also in automotive, construction and sailing sectors. Carbon Fibre Reinforced Polymers (CFRPs) bring lighter structures but with an impressive mechanical behaviour. Therefore, it seems to be important understanding the different degradation processes, es...

This work uses the strip yield model implemented in NASGRO software to estimate fatigue life under random loading. Simulated results were compared with experimental data previously obtained by the authors using different random loading processes in Al2024-T351. Test data under constant amplitude loading from different authors have been considered i...

This work analyses the influence that the type of geometry used to model a cylindrical contact has on fretting fatigue life predictions. It also studies the effect that the assumed fatigue crack shape has on fretting fatigue life predictions. The strain–stress fields are obtained using different finite elements models. These models consider the fol...

This paper is concerned with the application of the strip yield models implemented in NASGRO to estimate fatigue crack growth under random loading. The two different strip yield model options (constant constraint-loss (CCL) and variable constraint-loss (VCL)) implemented in the software are considered and compared. In addition, three crack grow rat...

Knowing the evolution of callus stiffness is very important in distraction osteogenesis and bone healing. It allows the characterization of the bone maturation process and the assessment of the moment to retire the fixator. A new distractor device that monitors the callus axial stiffness is presented in this study. It quantifies the callus stiffnes...

This paper presents two multiaxial fatigue life prediction models applied to a commercial dental implant. One model is called Variable Initiation Length Model and takes into account both the crack initiation and propagation phases. The second model combines the Theory of Critical Distance with a critical plane damage model to characterise the initi...

Un sistema de control de estabilidad en maquinaria pesada del tipo que incluye cadenas u orugas para desplazarse, basado en evaluación de riesgo de vuelco asociado a su posición de trabajo, incluye múltiples detectores que miden el valor de las reacciones en los puntos de apoyo de la máquina sobre el terreno, y la determinación en cada instante de...

Understanding the evolution of callus mechanical properties over time provides insights in the mechanobiology of fracture healing and tissue differentiation, can be used to validate numerical models, and informs clinical practice. Bone transport experiments were performed in sheep, in which a distractor type Ilizarov was implanted. The forces throu...

In the breast of adult women, glandular and fat tissues are intermingled and cannot be clearly distinguished. This work studies if this mixture can be treated as a homogenized tissue. A mechanical model is proposed for the mixture of tissues as a function of the fat content. Different distributions of individual tissues and geometries have been tri...

The load bearing characteristics of the intervened limb over time in vivo are important to know in distraction osteogenesis and bone healing for the characterization of the bone maturation process. Gait analyses were performed for a group of sheep in which bone transport was carried out. The ground reaction force was measured by means of a force pl...

Less Invasive Stabilization System femoral plates are currently accepted as a suitable fixation technique for supra-intercondylar femoral fractures. However, general agreement does not exist regarding the optimum design of this fixator type. Therefore, the aim of this article is to reduce the intrinsic Less Invasive Stabilization System complicatio...

In this article, the interior half-plane stress field resulting from the contact between a half-plane and a flat rounded punch is obtained in an explicit form. The punch is first subjected to a normal load, N, and later to a tangential load Q = µN, so a global sliding condition is achieved. The equations presented here are obtained assuming that th...

This paper analyses the influence that the type of geometry used to obtain the stress/strain fields in a cylindrical contact has on fretting fatigue life predictions. In addition, this work considers the effect that the fatigue crack shape assumed has on these fretting fatigue life predictions. The strain/stress fields are calculated using a series...

This work presents a method for assessing the fretting fatigue life by estimating the fatigue crack growth rate from the regime of microcracks to the final failure, which is achieved using a two-threshold small fatigue crack growth model. The propagation thresholds are associated with the interaction of the "monotonic plastic zone" and the "cyclic...

This paper proposes a multiaxial fatigue life model that considers the presence and cyclic relaxation of a residual stress field. Although the model has been developed for fretting fatigue under spherical contact conditions, and considers a residual stress field induced by specific laser and shot-peening treatments, its general structure can be app...

Fretting fatigue denotes the detrimental effect on a material arising from the cyclic sliding of two contacting surfaces with small relative displacements between them. One or both of the components in contact may be subject to bulk stresses caused by cyclic loads. The assessment of the fretting fatigue strength and life of any component is a compl...

This paper studies the fatigue behaviour of dental implants made of commercially pure titanium grade 4. This work analyses the influence of different factors: stress concentration at the external thread and the surface treatment. This objective is achieved by designing a series of fatigue tests in simple geometries (smooth specimens with and withou...

Highly Accelerated Life Testing (HALT) of any product consist in applying several types of loads for accelerated reliability analysis in order to find weaknesses during both design and development stages. Different environmental stress conditions like high rate thermal cycling and vibration are generally introduced during HALT. In this work, therma...

A precise information of the biomechanical properties of soft tissues is required to develop suitable simulation model, with which the distribution of stress and strain in the complex structures can be estimated. Many soft tissues have been mechanically characterized by stress relaxation tests under unconfined or confined compression. In general, f...

This paper analyses the influence of crack shape and the procedure used to calculate the stress distribution on the estimated fatigue life in a notched specimen. To estimate the crack shape, a series of interrupted tests at a various number of cycles was performed. Afterward, the specimens were broken to analyse crack shape. The stress intensity fa...

Bone remodelling in cortical bone is performed by the so-called basic multicellular units (BMUs), which produce osteons after completing the remodelling sequence. Burger et al. (2003) hypothesized that BMUs follow the direction of the prevalent local stress in the bone. More recently, Martin (2007) has shown that BMUs must be somehow guided by micr...

This paper analyses the effect of a wavy regular surface texturing on fretting fatigue life, and more specifically, studies the influence of this regular pattern on the initiation and crack propagation phases in fretting fatigue. In this work, an elastic—plastic finite element model (FEM) is used to simulate the contact between a half-plane and a c...