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Fiber Reinforced Elastomeric Isolators (FREIs) have been proposed as an alternative to Steel Reinforced Elastomeric Isolators (SREIs) and several studies have highlighted the advantages of this technology over conventional devices. When FREIs are unbonded to the top and bottom substructure, the bearings exhibit softening under imposed lateral deformations with or without instability depending on the aspect ratio of the device. Research studies available in literature have focused on the response of rectangular bearings when loaded in shear along their base. Very little is known on the lateral response of these devices under bidirectional shear loading. This study aims to assess the response of rectangular FREIs under combined axial and bidirectional shear loads and to show the effects of (i) the secondary shape factor of the bearing, of (ii) the axial pressure, of (iii) the horizontal loading direction on the stability of these devices. As result of a large set of analyses, stability domains have been derived which take into account all of the variables listed above. Based on the results of this work, simple to use design considerations can be derived. Results of this study contribute towards the real implementation of this technology particularly in developing regions of the world.

This work proposes a numerical methodology for the calculation of currents and voltages induced on underground pipelines by nearby overhead power lines. A previously developed quasi-3D methodology is extended, allowing the investigation of nonparallel routings of the pipelines with respect to the power lines. The proposed technique is based on a discretization of the pipeline path into several segments parallel to the power line. The section of the corridor corresponding to each pipeline segment is regarded as an electrical multi-port component, whose electrical parameters are extracted via finite element 2D analysis. Then, the obtained components are integrated into a network embodying the physical characteristics of the whole corridor. In this way, the circuital analysis is used to extend the capabilities of a standard two-dimensional field analysis. The proposed methodology is employed to simulate a pipeline running parallel to a power line for a distance of 12km. Afterwards, several nonparallel configurations – consisting of crossings between a pipeline and a power line – are assessed. The physical consequences of the crossing are discussed and a convergence study is performed to investigate the optimal pipeline subdivision procedure to be adopted for a set of different crossing angles.

The paper is related to the assessment of collapse mechanisms of historic masonry structures suffering settlements induced by ground movements. Two numerical strategies are adopted in order to study the influence of the settled zone on the cracking of masonry buildings: a discrete rigid block model and a continuous homogenized model. The first approach provides an estimate of the collapse load and failure pattern of masonry based on the lower bound theorem of limit analysis. The second approach is formulated in the framework of multi-surface plasticity and implemented in a FE code for the path-following non-linear analysis of masonry wall described as continuous anisotropic plate. Several settlement configurations, of masonry walls under moving ground support are investigated and the corresponding failure patterns resulting from the analysis are obtained resulting in local or global failure modes. The results of the two modeling formulations are compared and discussed in order to highlight the features of the two different approaches in the prediction of settlement-induced damage.

Since the beginning of their production, pneumatic tires have experienced tremendous improvements in structure and materials, becoming the dominant design in the world tires market. Nevertheless, relying upon pressurized air, they are affected by maintenance and security issues that can lead to fatal accidents. Therefore, tire-makers are investigating new tire designs, called Airless or Non-Pneumatic, with the aim of removing air-related problems. The research about such tires is still at an early stage, especially if compared to the one conducted on the pneumatic ones. In this paper, the development of a methodology capable of studying the mechanical behavior of a Non-Pneumatic Tire (NPT) by means of experimental data and numerical approach is illustrated. The experimental activities consisted of a scanner acquisition of the NPT and a footprint analysis for the calculation of the radial stiffness and contact patch pressure distribution. Moreover, the Digital Image Correlation (DIC) technique was applied to carry out a more specific study about the spoke’s deformation. From the acquired 3D model, a calculation of the NPT vertical deflection with finite element analysis (FEA) was performed—validating the model and then submitting it to a steady state analysis—that allows the simulation of a steady state rolling tire with the possibility to replicate different values of slip ratio. The results of the experimental activities are in good agreement with the ones obtained with FEA, further validating the developed methodology.

The analytical prediction of the effectiveness of fiber-reinforced polymer (FRP) in the confinement of a rectangular reinforced concrete (RC) column with a high aspect ratio (wall-like) still has an uncertain solution. In this paper, a numerical investigation of the axial response of RC wall-like columns strengthened with FRP systems was developed. Analytical solutions proposed in the literature for the assessment of the axial load capacity were presented and compared with each other and with the available experimental results. Moreover, non-linear finite element analysis was carried out, and the results were discussed, providing a simple model for the assessment of the axial compressive strength of wall-like RC columns strengthened with FRP.

Osteoporosis affects an increasing number of people every year and patient specific finite element analysis of the femur has been proposed to identify patients that could benefit from preventative treatment. The aim of this study was to demonstrate, verify, and validate an objective process for selecting tissues for use as the basis of phantomless calibration to enable patient specific finite element analysis derived hip fracture risk prediction. Retrospective reanalysis of patient computed tomography (CT) scans has the potential to yield insights into more accurate prediction of osteoporotic fracture. Bone mineral density (BMD) specific calibration scans are not typically captured during routine clinical practice. Tissue-based BMD calibration can therefore empower the retrospective study of patient CT scans captured during routine clinical practice. Together the method for selecting tissues as the basis for phantomless calibration coupled with the post-processing steps for deriving a calibration equation using the selected tissues provide an estimation of quantitative equivalent density results derived using calibration phantoms. Patient tissues from a retrospective cohort of 211 patients were evaluated. The best phantomless calibration resulted in a femoral strength (FS) [N] bias of 0.069 ± 0.07% over FS derived from inline calibration and a BMD [kg/cm3] bias of 0.038 ± 0.037% over BMD derived from inline calibration. The phantomless calibration slope for the best method presented was within the range of patient specific calibration curves available for comparison and demonstrated a small bias of 0.028 ± 0.054 HU/(mg/cm3), assuming the Mindways Model 3 BMD inline calibration phantom as the gold standard. The presented method of estimating a calibration equation from tissues showed promise for CT-based femoral fracture analyses of retrospective cohorts without readily available calibration data.

Context Primary hyperparathyroidism (PHPT) is associated with impaired bone quality and increased fracture risk. Reliable tools for the evaluation of bone quality parameters are not yet clinically available. Bone Strain Index (BSI) is a new metric for bone strength based on Finite Element Analysis from lumbar spine and femoral neck dual-energy x-ray absorptiometry (DXA) images. Objective To assess the lumbar spine (LS), femoral neck (FN), and total hip (TH) BSI in PHPT patients compared with controls and to investigate the association of BSI with vertebral fractures (VFs) in PHPT. Methods This case-control study enrolled 50 PHPT patients and 100 age- and sex-matched control subjects from an outpatient clinic. The main outcome measures were LS-BSI, FN-BSI, and TH-BSI. Results FN bone mineral density (BMD) and one-third distal radius BMD were lower in the PHPT group than in controls (FN 0.633 ± 0.112 vs 0.666 ± 0.081, P = 0.042; radius 0.566 ± 0.07 vs 0.625 ± 0.06, P < 0.001). PHPT group has significant lower TBS score compared with controls (1.24 ± 0.09 vs 1.30 ± 0.10, P < 0.001). BSI was significantly higher at LS (2.28 ± 0.59 vs 2.02 ± 0.43, P = 0.009), FN (1.72 ± 0.41 vs 1.49 ± 0.35, P = 0.001), and TH (1.51 ± 0.33 vs 1.36 ± 0.25, P = 0.002) in PHPT. LS-BSI showed moderate accuracy for discriminating VFs (AUC 0.667; 95% CI, 0.513-0.820). LS-BSI ≥ 2.2 and was a statistically significant independent predictor of VFs, with an adjusted odds ratio ranging from 5.7 to 15.1. Conclusion BSI, a DXA-derived bone quality index, is impaired in PHPT and may help to identify PHPT subjects at high risk of fractures.

In this study, we report the fabrication of two different three-dimensional (3D) architectures of regenerated silk (RS) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with embedded functionalities. 3D printed cylinders with an internal layer of PHBV and an external of calcium ions (Ca++) or potassium nitrate (KNO3) modified RS were designed to control the radial shrinkage, water uptake and compression strength. Such cylinders were then used as sutureless thermoresponsive clips, measuring the bursting resistance once applied on an anastomized porcine intestine. Experimental data are supported by finite element simulations that model the tube contraction, demonstrating the possibility to program the shape-changing behavior of 3D printed structures. Printing RS on PHBV, we obtained responsive 3D grids to external force with self-powering properties. The synergic effect obtained by combining materials on appropriate architectures paves the way to potential clinical applications ranging from monitoring of vital signs to sutureless sealant patches.

The application of the submodeling technique to finite element (FE) wear analyses has been recently proposed as an efficient solution to reduce the computational cost of the simulations and provide accurate numerical results. However, the method was validated only on single point contact cases. The present study proposes a generalization of the wear submodeling procedure that can be used to speed up FE wear simulations with multipoint contacts. The modified global–local procedure is applied and evaluated on a double contact pin on plate wear test using three-dimensional models developed in Ansys® mechanical APDL. Three different model geometries with different curvature radii at the contact regions were considered in order to replicate possible critical scenarios. Results suggest that an additional wear simulation step where the global model is used to simulate the first wear cycles is needed to correctly transfer the boundary conditions to the local models. The new proposed strategy demonstrates the possibility to extend the method to more general FE wear simulations by significantly reducing their computational cost.

Nowadays, fire-doors optimization is approached by using consolidated design guidelines and traditional materials, such as rock wool. Then, selected solution is directly tested in a mandatory fire-test. Unfortunately, few pieces of information could be retrieved either if the test succeeds or fails, which makes both improvements in the design and use of innovative materials difficult. Thus, in this work, a self-consistent finite element method (FEM) analysis is developed and assessed against experimental fire-test results, highlighting the critical parameters affecting the numerical simulations. Using this tool, a new fiberglass-containing foam, with improved acoustic and mechanical properties, as compared to the rock-wool, is studied as a potential insulating material for on-board fire-doors. The assessment of the performance of the new material demonstrates that, contrary to common believe, the effective thermal insulation capacity is not necessarily the critical factor in determining the fire-resistance of a fire-door. Using the validated FEM analysis, it has been proven that the reduction of the thermal bridges originated at the door edges allows, firstly, for the attainment of a fire-door 37% thinner and 61% lighter with respect to a traditional one, and, secondly, the use of new material as insulator in fire-doors that, even if less thermally capable, could improve other properties of the door, as an example its soundproofing.

Introduction Dentistry, therefore implantology, prosthetics, implant prosthetics or orthodontics in all their variants, are medical and rehabilitative branches that have benefited greatly from these methods of investigation to improve the predictability of rehabilitations. We will examine the Finite Element Method and Finite Element Analysis in detail. This method involves the simulation of mechanical forces from an environment with infinite elements, the real one, to a simulation with finite elements. Evidence acquisition The study searched MEDLINE databases from 2008 to 2018. Human use of FEM in vitro studies reported a contribution on oral rehabilitation through the use of FEM analysis. The initial search obtained 296 citations. After a first screening, the present revision considered the English-language works referred to human application of the FEM published in the last 10 years. Finally, 34 full texts were available after screening. Evidence synthesis The ultimate aim of this review is to point out all the progress made in the field of bioengineering and therefore, thanks to this, in the field of medicine. Instrumental investigations such as FEM are an excellent tool that allows the evaluation of anatomical structures and any facilities for rehabilitation before moving on to experimentation on animals, so as to have mechanical characteristics and satisfactory load cycle testing. Conclusions FEM analysis contributes substantially to the development of new technologies and new materials in the biomedical field, being able to perform a large number of simulations without the need for patients or to perform human tests. Thanks to the 3D technology and to the reconstructions of both the anatomical structures and eventually the alloplastic structures used in the rehabilitations it is possible to consider all the mechanical characteristics, so that they can be analyzed in detail and improved where necessary. It is possible thanks to these methods to know what are the ideal characteristics of a material to promote an oral rehabilitation, so we know the characteristics, it remains only to take a step in the field of the industry for the construction of materials close to these characteristics.

In the present work, a preliminary design of an eco-sustainable bamboo electric treadmill bike is carried out. It is a new means of transport with zero environmental impact that also allows to overcome the main disadvantage of the indoor training. Bamboo, as an eco-friendly material, has great potential as construction material for bike frames because it represents an alternative for more traditional materials such as steel, aluminum, and composite. A finite element model of the designed prototype is developed and then validated using Abaqus commercial code following the UNI EN 14764 static standard. Numerical analyses show good structural behavior of the designed frame in compliance with the regulations.

OBJECTIVES Reinforcements for the pulmonary autograft (PA) in the Ross operation have been introduced to avoid the drawback of conduit expansion and failure. With the aid of an in silico simulation, the biomechanical boundaries applied to a healthy PA during the operation were studied to tailor the best implant technique to prevent reoperation. METHODS Follow-up echocardiograms of 66 Ross procedures were reviewed. Changes in the dimensions and geometry of reinforced and non-reinforced PAs were evaluated. Miniroot and subcoronary implantation techniques were used in this series. Mechanical stress tests were performed on 36 human pulmonary and aortic roots explanted from donor hearts. Finite element analysis was applied to obtain high-fidelity simulation under static and dynamic conditions of the biomechanical properties and applied stresses on the PA root and leaflet and the similar components of the native aorta. RESULTS The non-reinforced group showed increases in the percentages of the mean diameter that were significantly higher than those in the reinforced group at the level of the Valsalva sinuses (3.9%) and the annulus (12.1%). The mechanical simulation confirmed geometrical and dimensional changes detected by clinical imaging and demonstrated the non-linear biomechanical behaviour of the PA anastomosed to the aorta, a stiffer behaviour of the aortic root in relation to the PA and similar qualitative and quantitative behaviours of leaflets of the 2 tissues. The annulus was the most significant constraint to dilation and affected the distribution of stress and strain within the entire complex, with particular strain on the sutured regions. The PA was able to evenly absorb mechanical stresses but was less adaptable to circumferential stresses, potentially explaining its known dilatation tendency over time. CONCLUSIONS The absence of reinforcement leads to a more marked increase in the diameter of the PA. Preservation of the native geometry of the PA root is crucial; the miniroot technique with external reinforcement is the most suitable strategy in this context.

Fiber-reinforced elastomeric isolators (FREIs) are generally installed in unbonded configurations. Because of the simultaneous application of axial loads and large lateral deformations, instability of these bearings is a major concern. This paper shows the results of a large series of 3D finite element analyses (FEAs) on square-shaped FREIs. The analyses aimed at obtaining easy to use design charts where the stability limits of these devices can be rapidly determined. The output of the analyses is compared to analytical results available in literature and the limitations of well-known closed form solutions are discussed.

The paper presents an experimental and Finite Element (FE) numerical analysis of the behavior of unprotected log-haus timber walls in fire conditions under in-plane compressive loads. The aim is to assess their overall structural performance and to provide possible design suggestions. In doing so, the main results derived from a full-scale experimental test of a log-haus specimen subjected to the standard fire curve and loaded in-plane in compression are first described. FE numerical simulations are then carried out, to further assess the test results and to perform - based on the rather close correlation between test and FE results - a parametric study on the examined structural system. The effects of several influencing parameters are then investigated, including the presence of an initial geometrical out-of-plane global curvature, the possible exposure to fire of orthogonal logs and carpentry joints acting as lateral outriggers for the main log-haus wall, and the compressive loading ratio acting in combination with the fire loading. The most significant effects of such influencing parameters are highlighted in terms of overall buckling resistance and failure mechanisms for the examined walls in fire conditions, providing evidence for the reduction of their actual load carrying capacity. In conclusion, aiming to derive useful design suggestions, a possible extension to log-haus systems of the “Reduced Cross-Section Method” (RCSM) currently in use for the verification of fire exposed timber members is proposed.

This paper deals with the experimental and numerical investigations of the structural behaviour of a rolling stock's seats system under static and fatigue loading conditions, aimed to assess the reliability of some multiaxial fatigue failure criteria implemented in the FE model. According to the NF F31–119 standard, a specific full-scale multiaxial testing machine has been used for the fatigue test. During the test, a visual inspection approach with a detection interval of 3·105 cycles has been adopted. After 1.2·106 cycles the test has been stopped and a Liquid Penetrant Inspection (LPI) has been carried out in order to detect accurately cracks nucleation and propagation. Moreover, numerical analyses, based on the Finite Elements (FE) Method, have been performed on the EN-AW 6060 T5 aluminium alloy structure of a rolling stock's seats to predict the most affected zones where the cracks nucleation may occur under multiaxial fatigue loads. Since the in-service applied loads belong to Multiaxial High-Cycle Fatigue (MHCF) load class, Sines, Crossland and Dang Van criteria have been used to post-process the predicted results achieved by the FE analyses. For validation purpose, numerical and experimental results have been compared. According to the numerical-experimental results comparison, Dang Van criterion provided the best level of accuracy.

Partial discharge (PD) activity in the insulation system of an electrical equipment can determine the failure of the whole apparatus. PD sensors are widely used in high-voltage electrical systems as the main elements of a detecting system oriented to real time monitoring. Recently, non-invasive sensors have been proposed in industrial applications for cable and other sensitive electrical parts: they are based both on capacitive and on the electromagnetic radiating coupling. In order to assess the real performance of a new sensor produced by a high voltage AC cables manufacturer, the paper proposes electromagnetic fullwave simulation results.

The paper deals with the application of LiABlock_3D, a novel software tool developed at the University of Naples Federico II, to the case study of an historic masonry viaduct listed by UNESCO as World Heritage Site. LiABlock_3D analyses masonry structures under seismic lateral loads and automatically predict the potential failure modes of complex assemblages in terms of local and global collapse mechanisms. The numerical formulation is based on limit equilibrium analysis and mathematical programming is used to solve the contact problem. Masonry structures are represented as a collection of three-dimensional rigid blocks. Once the geometry of the construction has been generated (i.e. using different CAD tools or MATLAB® scripts for parametric analysis), the numerical model requires few parameters as input data, such as the unit weight of materials and the friction coefficient. Several loading conditions can be considered, assuming different loading axis and load distribution (uniform and/or concentrated loads can be applied). With respect to failure condition, LiABlock_3D considers no-tension, frictional contact interfaces with infinite compressive strength. Opening and sliding failure conditions are considered. In order to show the potentialities and limitations of the developed software, a comparison of the outputs provided by LiABlock_3D with those obtained by Finite Element Analysis is presented and discussed as well.

In this paper, we introduce a novel type of transdermal drug delivery device (TD3) with a micro-electro-mechanical system (MEMS) design using computer-aided design (CAD) techniques as well as computational fluid dynamics (CFD) simulations regarding the fluid interaction inside the device during the actuation process. For the actuation principles of the chamber and microvalve, both thermopneumatic and piezoelectric principles are employed respectively, originating that the design perfectly integrates those principles through two different components, such as a micropump with integrated microvalves and a microneedle array. The TD3 has shown to be capable of delivering a volumetric flow of 2.92 &times, 10&minus, 5 cm3/s with a 6.6 Hz membrane stroke frequency. The device only needs 116 Pa to complete the suction process and 2560 Pa to complete the discharge process. A 38-microneedle array with 450 &micro, m in length fulfills the function of permeating skin, allowing that the fluid reaches the desired destination and avoiding any possible pain during the insertion.

This article focuses on the static structural analysis of a tibial intramedullary nail, carried out by the finite element method. The investigated subject is concerned with the issue of frictional contacts that, generating a non-linear problem, play an important role in numerical analyses. Experimental tests were also developed on tibial intramedullary nail specimens. The experimental results, in terms of force–displacement, were used to calibrate and validate the finite element analysis, by tuning the contact parameters available in the software.

Aims This study aimed to compare the acute expansion behaviour of a polymer-based bioresorbable scaffold and a second-generation metallic DES platform in a realistic coronary artery lesion model. Experimental mechanical data with conventional methods have so far shown little difference between metallic stents and currently available polymer-based bioresorbable scaffolds (BRS). Nevertheless, differences in acute results have been observed in clinical studies comparing BRS directly with metallic DES platforms. Methods and results We examined the expansion behaviour of the bioresorbable vascular scaffold (3.0×18 mm Absorb BVS; Abbott Vascular, Santa Clara, CA, USA) and a metallic DES (3.0×18 mm XIENCE Prime; Abbott Vascular) after expansion at 37°C using identical coronary artery stenosis models (in total 12 experiments were performed). Device expansion was compared during balloon inflation and after deflation using microscopy to allow assessment of plaque recoil. Minimal lumen diameter (MLD) and minimal lumen area (MLA) and stent eccentricity were quantified from optical coherence tomography (OCT) imaging at nominal diameter and after post-dilation at 18 atm. The MLA in the models with BVS deployed was 4.92±0.17 mm² while in the metallic DES it was 5.40±0.13 mm2 (p=0.02) at nominal pressure (NP), and 5.41±0.20 and 6.07±0.25 mm2 (p=0.02), respectively, after expansion at 18 atm. Stent eccentricity index at the MLA was 0.71±0.02 in BVS compared to 0.81±0.02 in the metal stent at NP (p=0.004), and 0.73±0.03 compared to 0.75±0.02 at 18 atm (p=0.39). Conclusions Results obtained in this in vitro lesion model were comparable to the results in randomised clinical trials comparing BVS and XIENCE stents in vivo. Such models may be useful in future BRS developments to predict their acute response in vivo in eccentric lesions.

This paper discusses the seismic behavior of reinforced concrete (RC) bridge structures, focusing on the shear&ndash, flexure interaction phenomena. The assessment of reinforced concrete bridges under seismic action needs the ability to model the effective non-linear response in order to identify the relevant failure modes of the structure. Existing RC bridges have been conceived according to old engineering practices and codes, lacking the implementation of capacity design principles, and therefore can exhibit premature shear failures with a reduction of available strength and ductility. In particular, recent studies have shown that the shear strength can decrease with the increase of flexural damage after the development of plastic hinges and, in some cases, this can cause unexpected shear failures in the plastic branch with a consequent reduction of ductility. The aim of the research is to implement those phenomena in a finite-element analysis. The proposed model consists of a flexure fiber element coupled with a shear and a rotational slip spring. The model has been implemented in the OpenSEES framework and calibrated against experimental data, showing a good ability to capture the overall response.

The Simons Observatory (SO) will make precision temperature and polarization measurements of the cosmic microwave background (CMB) using a series of telescopes which will cover angular scales between one arcminute and tens of degrees, contain over 60,000 detectors, and sample frequencies between 27 and 270 GHz. SO will consist of a six-meter-aperture telescope coupled to over 30,000 detectors along with an array of half-meter aperture refractive cameras, which together couple to an additional 30,000+ detectors. SO will measure fundamental cosmological parameters of our universe, find high redshift clusters via the Sunyaev-Zeldovich effect, constrain properties of neutrinos, and seek signatures of dark matter through gravitational lensing. In this paper we will present results of the simulations of the SO large aperture telescope receiver (LATR). We will show details of simulations performed to ensure the structural integrity and thermal performance of our receiver, as well as will present the results of finite element analyses (FEA) of designs for the structural support system. Additionally, a full thermal model for the LATR will be described. The model will be used to ensure we meet our design requirements. Finally, we will present the results of FEA used to identify the primary vibrational modes, and planned methods for suppressing these modes. Design solutions to each of these problems that have been informed by simulation will be presented., Comment: 14 pages, 10 figures, Proceedings of SPIE

Wear debris from ultra-high-molecular-weight polyethylene components used for joint replacement prostheses can cause significant clinical complications, and it is essential to be able to predict implant wear accurately in vitro to prevent unsafe implant designs continuing to clinical trials. The established method to predict wear is simulator testing, but the significant equipment costs, experimental time and equipment availability can be prohibitive. It is possible to predict implant wear using finite element methods, though those reported in the literature simplify the material behaviour of polyethylene and typically use linear or elastoplastic material models. Such models cannot represent the creep or viscoelastic material behaviour and may introduce significant error. However, the magnitude of this error and the importance of this simplification have never been determined. This study compares the volume of predicted wear from a standard elastoplastic model, to a fractional viscoelastic material model. Both models have been fitted to the experimental data. Standard tensile tests in accordance with ISO 527-3 and tensile creep recovery tests were performed to experimentally characterise both (a) the elastoplastic parameters and (b) creep and relaxation behaviour of the ultra-high molecular weight polyethylene. Digital image correlation technique was used in order to measure the strain field. The predicted wear with the two material models was compared for a finite element model of a mobile-bearing unicompartmental knee replacement, and wear predictions were made using Archard’s law. The fractional viscoelastic material model predicted almost ten times as much wear compared to the elastoplastic material representation. This work quantifies, for the first time, the error introduced by use of a simplified material model in polyethylene wear predictions, and shows the importance of representing the viscoelastic behaviour of polyethylene for wear predictions.

Purpose: The objective of this investigation is to study prosthodontics and internal components resistance to the masticatory stress and considering different force directions by using Finite Element Method analysis (FEM). The structural materials of the components are usually Titanium alloy grade 4 or 5 and thus, guarantee the integration of the fixture in the bone due to the osteointegration phenomena. Even if the long-term dental implant survival rate is easy to be obtained and confirmed by numerous researches, the related clinical success, due to the alteration of the mechanical and prosthodontics components is still controversial. Methods: By applying engineering systems of investigations like FEM and Von Mises analyses, it has been investigated how dental implant material was held against the masticatory strength during the dynamic masticatory cycles. A three-dimensional system involved fixture, abutment and the connection screws, which were created and analyzed. The elastic features of the materials used in the study were taken from recent literature data. Results: Data revealed a different response for both types of devices, although implant neck and dental abutment showed better results for all conditions of loading while the abutment screw represented aweak point of the system. Conclusion: The data of this virtual model showed all the features of different prosthetic retention systems under the masticatory load. Clinicians should find better prosthetic balance in order to better distribute the stress over the component and to guarantee patients’ clinical long-term results. Purpose: The objective of this investigation is to study prosthodontics and internal components resistance to the masticatory stress and considering different force directions by using Finite Element Method analysis (FEM). The structural materials of the components are usually Titanium alloy grade 4 or 5 and thus, guarantee the integration of the fixture in the bone due to the osteointegration phenomena. Even if the long-term dental implant survival rate is easy to be obtained and confirmed by numerous researches, the related clinical success, due to the alteration of the mechanical and prosthodontics components is still controversial. Methods: By applying engineering systems of investigations like FEM and Von Mises analyses, it has been investigated how dental implant material was held against the masticatory strength during the dynamic masticatory cycles. A three-dimensional system involved fixture, abutment and the connection screws, which were created and analyzed. The elastic features of the materials used in the study were taken from recent literature data. Results: Data revealed a different response for both types of devices, although implant neck and dental abutment showed better results for all conditions of loading while the abutment screw represented aweak point of the system. Conclusion: The data of this virtual model showed all the features of different prosthetic retention systems under the masticatory load. Clinicians should find better prosthetic balance in order to better distribute the stress over the component and to guarantee patients’ clinical long-term results.

Objective To assess the influence of implant thread shape and inclination on the mechanical behaviour of bone-implant systems. The study assesses which factors influence the initial and full osseointegration stages. Methods Point clouds of the original implant were created using a non-contact reverse engineering technique. A 3D tessellated surface was created using Geomagic Studio ® software. From cross-section curves, generated by intersecting the tessellated model and cutting-planes, a 3D parametric CAD model was created using SolidWorks ® 2017. By the permutation of three thread shapes (rectangular, 30° trapezoidal, 45° trapezoidal) and three thread inclinations (0°, 3° or 6°), nine geometric configurations were obtained. Two different osseointegration stages were analysed: the initial osseointegration and a full osseointegration. In total, 18 different FE models were analysed and two load conditions were applied to each model. The mechanical behaviour of the models was analysed by Finite Element (FE) Analysis using ANSYS ® v. 17.0. Static linear analyses were also carried out. Results ANOVA was used to assess the influence of each factor. Models with a rectangular thread and 6° inclination provided the best results and reduced displacement in the initial osseointegration stages up to 4.58%. This configuration also reduced equivalent VM stress peaks up to 54%. The same effect was confirmed for the full osseointegration stage, where 6° inclination reduced stress peaks by up to 62%. Significance The FE analysis confirmed the beneficial effect of thread inclination, reducing the displacement in immediate post-operative conditions and equivalent VM stress peaks. Thread shape does not significantly influence the mechanical behaviour of bone-implant systems but contributes to reducing stress peaks in the trabecular bone in both the initial and full osseointegration stages.

Self-expanding stents made of Nitinol, a Nickel–Titanium shape memory alloy, are used in standard medical implants for the treatment of cardiovascular diseases. Despite the increasing success, clinical studies have reported stent failure after the deployment in the human body, thus undermining patient’s safety and life. This study aims to fill the gap of reliable assessment of the fatigue life of Nitinol stents. We propose a global computational design method for preclinical validation of Nitinol stents, which can be extended to patient-specific computations. The proposed methodology is composed of a mechanical finite element analysis and a fatigue analysis. The latter analysis is based on a novel multiaxial fatigue criterion of the Dang Van type, combining the shakedown response of the stent and the complexity of phase transformation taking place within the material. The method is implemented in the case of a carotid artery stent. The implant configuration as well as the applied cyclic loading are shown to affect material phase evolution as well as stent lifetime. The comparison with the results obtained by applying a strain-based constant-life diagram approach allows to critically discuss both fatigue criteria and to provide useful recommendations about their applicability.

Total hip arthroplasty is a ubiquitously successful orthopedic surgical procedure, whose prevalence is rising worldwide. While many investigations focus on characterizing periprosthetic pathophysiology, the objective of our research is to develop and describe multi-metric assemblies as a first step toward creating a patient-specific mobility index that rehabilitators and orthopedic surgeons can utilize for prescribing their respective procedures. In total, 48 total hip arthroplasty patients (both cemented and uncemented) undergoing unilateral, primary surgery went through computed tomographic scans and gait analysis measurements both before and 1 year following their surgery. Altogether, the reported quantitative metrics include 11 spatial and temporal gait parameters, muscle density, and electromyography signals from the rectus femoris, vastus lateralis, and vastus medialis, and bone mineral density values from bioimage analysis around the implant stem. We found that measured parameters from a subgroup were sensitive to changes observed during patient recovery, implicating the predictive sensitivity of these patient conditions. Most post-operative gait parameters changed significantly, while electromyography data indicated few significant differences. Moreover, results from bioimage analyses indicate a general reduction of periprosthetic bone mineral density after 1 year, in association with increasing density of the quadriceps muscles. Furthermore, this work identifies which quantitative metrics undergo the greatest variation after total hip arthroplasty and demonstrates the clinical feasibility of a multimodal approach to mobility assessment that may ultimately support decision-making for post-surgical rehabilitation protocols.

Seismic retrofitting and vertical addition of existing buildings have been investigated.Different alternatives have been proposed for the two structural modification interventions.The TOPSIS MCDM method has been used for selecting the best alternative.Sensitivity analyses have proved the objectivity of the solutions found. In the current paper a novel procedure to select the optimal solution both for seismic retrofitting of existing RC buildings and for super-elevation of existing masonry constructions has been implemented by using three different Multi-Criteria Decision Making (MCDM) (TOPSIS, ELECTRE and VIKOR) methods.The procedure application has been faced with reference to two case studies.The first intervention has been studied on a real full-scale 3D RC structure retrofitted with different seismic protection devices mainly based on metal materials, whose performances were experimentally evaluated in a previous research project. All the applied MCDM methods have provided the same result, that is the dominating role exerted by aluminium shear panels for seismic retrofitting of the analysed structure.On the other hand, different innovative and traditional constructive systems have been examined to increase the number of floors of existing masonry buildings. The effectiveness of these interventions in improving the base building behaviour has been proved on a typical building of the South Italy. The study results, achieved by using the three MCDM methods inspected, have provided as an optimal solution the cold-formed steel systems thanks to their prerequisites of lightness, economy and sustainability.

We present the optical realization and characterization of complex suspended microchannel resonator (SMR) for biomechanical sensing applications. We exploit the flexibility of two-photon direct laser writing to optimize a highly versatile fabrication strategy based on a shell-writing procedure with the aim to reduce fabrication time of big inlet/outlet sections compatible with most microfluidic systems for lab-on-chip. Compared with standard microfabrication techniques, requiring several technological steps to obtain suspended hollow structures, this method allows to fabricate complex SMR sensors in only one fabrication step by virtue of its intrinsically 3-D nature. The realized resonant structure was characterized by laser doppler vibrometry, showing good agreement with finite-element methods simulations and an experimental quality factor of the fundamental mode of $\sim 60.$ [2014-0309]

This paper describes a theoretical investigation on the response of “all-steel” dismountable buckling restrained braces (BRBs) through the analysis of finite element models (FEMs). The focus of this investigation is on a special type of BRB developed for seismic upgrading of existing reinforced concrete buildings and experimentally tested previously. After a short summary of experimental results, the paper describes the finite element models and the analysis results. Subsequently, a discussion addresses the following issues: (i) influence of the core-to-casing clearance; (ii) influence of spacing of connections along the casing longitudinal axis; (iii) compression-to-tension strength ratio; (iv) core buckling wavelengths and core-to-casing interaction forces. Finally, the paper presents a comparison of numerical results and available analytical models.

This paper introduces and investigates a compliant spherical 3R open chain that is obtained by the in-series connection of three identical circularly-curved beam flexures with coincident centers of curvature and mutually orthogonal axes of maximum rotational compliance. The considered open chain is intended to be used directly as a spherical mechanism in pointing devices or as a complex spherical flexure for the development of spatial parallel manipulators. The compliance matrix of the proposed chain is first determined via an analytical procedure. After finite element validation, the obtained equations are used in a parametric study to assess the influence of circularly-curved beam flexure geometric parameters on the overall stiffness performances of the considered compliant spherical 3R open chain. In addition, comparison with an equivalent compliant spherical chain employing straight beam flexures is reported to highlight the added benefits of using circularly-curved beam flexures in terms of reduced parasitic motions.

Fires following road or railway accidents may escalate and cause catastrophic loss of containment and extremely severe final scenarios when hazardous material tankers are engulfed in flames. A heat-resistant coating is usually adopted to protect such tankers. However, defects may form on the coating due to wear, erosion, or accidental failures, thereby affecting the effectiveness of the thermal protection. In the present study, a methodology was developed to assess the performance of thermal protection coatings in the presence of defects. A thermal model based on finite element modeling (FEM) was developed to reproduce the behavior of tankers coated with defective insulation when exposed to fires. Experimental data were used to validate the model, which allowed to determine the temperature profile of tank shell with respect to time under different fire conditions. Specific key performance indicators (KPIs), calculated on the basis of the results of FEM simulations, were defined. The KPIs allow the identification of threshold conditions in which fireproofing performance is degraded and jeopardizes the structural integrity of the protected vessel when involved in fire. An approach based on the KPIs was developed to support the implementation of on-condition inspection-based maintenance strategies of thermal coatings.

A recent study [1] has discussed the accuracy of the nodal elastic stresses of zero thickness interface elements when fictitious elastic parameters (often called penalty stiffness factors) are used. These stresses, commonly used to calculate the triggering conditions of the opening of the interface simulating a discrete crack in quasi-brittle materials, are affected by non-negligible errors if the in- terfaces are embedded in unstructured/irregular meshes. A procedure to avoid these errors has been proposed for homogeneous materials [1] and bi-material interfaces [2]. Accurate nodal stresses are re- covered if certain geometry-dependent pre-processed coefficients are used. In this paper, this method is proposed in the analysis of Historical Stone Masonry Walls: zero-thickness interface elements rep- resent the interaction between stones of irregular shape. The crack opening triggering conditions are calculated for two identical meshes with rigid continuous elements representing the stones and fic- titiously elastic zero-thickness interfaces representing the mortar layers. This paper shows that the use of the proposed coefficients significantly changes the values of the interface stresses leading to different configurations of the cracking onset.

During the last decades, several macro-models have been proposed for the modelling of the infill panels' contribution to the lateral strength of frames. Despite all this effort, a robust model, which takes into account the influence of the vertical load, is not yet available. Furthermore, the influence of the very common case of infill walls with openings, such as windows and doors, has been neglected in all the code provisions that have been published so far. In this paper, an updated macro-model, based on the equivalent pin-jointed diagonal compressive strut, is presented. The proposed macro-model is able to represent the stiffening effect of the infill panel with openings by taking into account both the size of the opening and the vertical load acting on the frame. Detailed and in-depth parametrical investigation, based on finite element analysis, shows that the proposed mathematical macro-model can be used as a reliable and useful tool for the determination of the equivalent compressive strut width since it accounts for a large number of parameters, which are not generally accounted for by the already available models in the literature.

Monolithic Flexure-based Compliant Mechanisms (MFCM) can be used to conceive nonlinear springs with a desired load-displacement profile at one point of their structure. For a given MFCM topology, these particular springs can be conveniently dimensioned by resorting to the well-known Pseudo-Rigid-Body approximation, whose accuracy strongly depends on the modelling precision of the flexures’ principal compliance. For various types of flexures, closed-form solutions have been proposed, which express the compliance factors as functions of the flexure dimensions. Nonetheless, the accuracy of these relations is limited to slender, beam-like hinges undergoing rather small deflections. In order to overcome such limitations, this paper provides empirical equations, derived from finite element analysis, that can be used for the optimal dimensioning of circular, elliptical, and corner-filleted flexural hinges with general aspect ratios, on the basis of both principal compliance and maximum bearable stress. At first, an accuracy comparison with previously published results is provided. Then, as a case study, a nonlinear spring based on a double slider-crank MFCM and with a desired load-displacement profile is dimensioned and verified via finite element analysis. The corresponding MFCM prototype, produced by means of water jet cutting, is finally tested on a tensile stage. Both numerical and experimental results confirm that the aforementioned empirical equations outperform the closed-form solutions provided in the past literature when modelling thick cross-section hinges undergoing significant deflections. Monolithic Flexure-based Compliant Mechanisms (MFCM) can be used to conceive nonlinear springs with a desired load-displacement profile at one point of their structure. For a given MFCM topology, these particular springs can be conveniently dimensioned by resorting to the well-known Pseudo-Rigid-Body approximation, whose accuracy strongly depends on the modelling precision of the flexures’ principal compliance. For various types of flexures, closed-form solutions have been proposed, which express the compliance factors as functions of the flexure dimensions. Nonetheless, the accuracy of these relations is limited to slender, beam-like hinges undergoing rather small deflections. In order to overcome such limitations, this paper provides empirical equations, derived from finite element analysis, that can be used for the optimal dimensioning of circular, elliptical, and corner-filleted flexural hinges with general aspect ratios, on the basis of both principal compliance and maximum bearable stress. At first, an accuracy comparison with previously published results is provided. Then, as a case study, a nonlinear spring based on a double slider-crank MFCM and with a desired load-displacement profile is dimensioned and verified via finite element analysis. The corresponding MFCM prototype, produced by means of water jet cutting, is finally tested on a tensile stage. Both numerical and experimental results confirm that the aforementioned empirical equations outperform the closed-form solutions provided in the past literature when modelling thick cross-section hinges undergoing significant deflections.

This paper introduces and investigates a novel Spherical Flexure (SF), specifically conceived for application on spherical compliant mechanisms. The flexure features an arc of a circle as a centroidal axis and an annulus sector as cross-section, circle and annulus having a common center coinciding to that of the desired spherical motion. In this context, each element of the SF spatial compliance matrix is analytically computed as a function of both flexure dimensions and employed material. The theoretical model is then validated by relating analytical data with the results obtained through three-dimensional Finite Element Analysis. Finally, SFs are compared to Circularly Curved-Beam Flexures (CCBFs) in terms of parasitic motions.

Dilated cardiomyopathy is a heart disease characterized by both left ventricular dilatation and left ventricular systolic dysfunction, leading to cardiac remodeling and ultimately heart failure. We aimed to investigate the effect of dilated cardiomyopathy on the pump performance and myocardial wall mechanics using patient-specific finite element analysis. Results evinced pronounced end-systolic wall stress on left ventricular wall of patients with dilated cardiomyopathy as compared to that of normal hearts. In dilated cardiomyopathy, both end-diastolic and end-systolic pressure–volume relationships of left ventricle and right ventricle were shifted to the right compared to controls, suggesting reduced myocardial contractility. We hereby propose that finite element analysis represents a useful tool to assess the myocardial wall stress and cardiac work, which are responsible for progressive left ventricular deterioration and poor clinical course.

Numerical simulations on stiffened composite panels have been performed in order to investigate the influence of fibre bridging phenomenon on the onset and on the evolution of skin-stringer debonding. A novel numerical procedure for delamination growth simulation, implemented in ANSYS® FEM code by Ansys Parametric Design Language and enhanced to take into account G Ic variations related to the fibre bridging phenomenon, has been used to numerically simulate the skin-stringer separation. Indeed, fibre-reinforced composites can develop high fibre bridging under mode I (peeling) delamination growth due to the additional resistance to crack opening offered by delaminated fibres, leading to a significant increase of mode I critical strain energy release rate. Within the present paper, a limited sensitivity analysis is presented to assess the influence of geometrical parameters of stiffened composite panels on the fibre bridging relevance in skin-stringer debonding in terms of debonded area.

Round conductive bars embedded in semi-closed slots are frequently used in the construction of electric machinery, for instance in the squirrel cage of induction motors. Frequently, such as in the study of induction motor steady-state performance at rated slip, it is useful to estimate the slot leakage inductance of these conductors under the hypothesis of no eddy currents and no magnetic saturation. This is usually done through simple approximated analytical formulas available in the literature. In this paper, an improved explicit ready-to-use leakage inductance expression for circular bars embedded in semi-closed slots is derived by solving Poisson's equation in the slot domain. The precision of the proposed formulation is assessed against Finite Element Analysis (FEA) for various slot geometries and is shown to always give very accurate results, with errors below 2%. Conversely, approximated simplified formulas available from the literature are demonstrated to possibly give large errors, which exceed 20% for some explored slot geometries.

Squirrel-cage induction motors are the most widely used type of electric machinery in industrial applications thanks to their rugged, cheap and robust construction. For the fast prediction of induction motor steady-state performance without the need for time-consuming finite-element analyses, the equivalent circuit parameters of the machine need to be calculated, including rotor slot leakage inductances. This paper, in particular, proposes a new improved analytical formula to determine the rotor slot leakage inductance in squirrel-cage induction motors with rectangular-shaped bars. The formula is obtained by solving Poisson's equation in the slot domain. Results are assessed by comparison against Finite Element Analysis (FEA). The precision of the presented methodology is also compared to that of approximated analytical models available from the literature. The comparison shows that the accurate formula proposed is in excellent agreement with FEA with errors below 2%, while the simplified model generally leads to errors above 10% which increase as the height-to-width bar ratio decreases.

An innovative epiphyseal device has been recently proposed claiming an effective bone–prosthesis load transfer and a nearly physiological bone stresses distribution. However preliminary experimental tests showed a 23% weakening of the femoral neck after implantation. Aim of this study was to revise the prosthesis geometry with the goal of enhancing the femoral neck strength after implantation, while maintaining unchanged the initial conceptual design. To this aim, the risk of femoral neck fractures, prosthesis fractures, aseptic loosening and excessive bone resorption were addressed through a validated finite element procedure following a systematic approach. The initial prosthesis geometry was revised to reduce each investigated failure risk below the threshold of acceptance (100%). The new geometry was re-assessed to verify the effectiveness of the revision. The first design was predicted to locally induce high bone strains and cement stresses, which translated in a risk of bone and cement failure exceeding the threshold of acceptance (>100%). The revised design preserved a good stability of the device, contemporary reducing the risk for bone (45%) and cement (60%) failure. If results will be confirmed by statistical and clinical experimentations, current clinical indications for hip epiphyseal devices might be extended.

A linear array of eight individual addressable microelectrodes has been developed in order to perform high-throughput scanning electrochemical microscopy (SECM) imaging of large sample areas in contact regime. Similar to previous reports, the soft microelectrode array was fabricated by ablating microchannels on a polyethylene terephthalate (PET) film and filling them with carbon ink. Improvements have been achieved by using a 5 μm thick Parylene coating that allows for smaller working distances, as the probe was mounted with the Parylene coating facing the sample surface. Additionally, the application of a SECM holder allows scanning in contact regime with a tilted probe, reducing the topographic effects and assuring the probe bending direction. The main advantage of the soft microelectrode array is the considerable decrease in the experimental time needed for imaging large sample areas. Additionally, soft microelectrode arrays are very stable and can be used several times, since the electrode surface can be regenerated by blade cutting. Cyclic voltammograms and approach curves were recorded in order to assess the electrochemical properties of the device. An SECM image of a gold on glass chip was obtained with high resolution and sensitivity, proving the feasibility of soft microelectrode arrays to detect localized surface activity. Finite element method (FEM) simulations were performed in order to establish the effect of diffusion layer overlapping between neighboring electrodes on the respective approach curves.

International audience; This paper presents a method to track in real-time a 3D textureless object which undergoes large deformations such as elastic ones, and rigid motions, using the point cloud data provided by an RGB-D sensor. This solution is expected to be useful for enhanced manipulation of humanoid robotic systems. Our framework relies on a prior visual segmentation of the object in the image. The segmented point cloud is registered first in a rigid manner and then by non-rigidly fitting the mesh, based on the Finite Element Method to model elasticity, and on geometrical point-to-point correspondences to compute external forces exerted on the mesh. The real-time performance of the system is demonstrated on synthetic and real data involving challenging deformations and motions.

This paper introduces a method able to track in real-time a 3D elastic deformable objects which undergo fractures, using the point cloud data provided by an RGB-D sensor. Our framework relies on a prior visual segmentation of the object in the image. The segmented point cloud is registered by non-rigidly fitting the mesh, based on the Finite Element Method to physically model elasticity, and on geometrical point-to-point correspondences to compute external forces exerted on the mesh. Fractures are handled by processing the stress tensors computed on the mesh of the FEM model, in order to detect fracturable nodes. Local remeshing around fracturable nodes is then performed to propagate the fracture. The real-time performance of the system is demonstrated on real data involving various deformations and fractures.

This paper reports the optimization process of a MW-size, medium voltage, squirrel cage induction motor for industrial applications. Starting from an existing construction, the aim of the optimization is to maximize the induction machine power density, while fulfilling high demanding, specific international Oil&Gas industry regulations. For every considered design, the motor performance is estimated by means of an algorithm based on T-type equivalent circuit. The circuit parameters are determined with a combination of magnetostatic and time harmonic Finite Elements Analysis (FEA), together with analytical formulas. This approach allows the evaluation of the precise parameters dependency on punctual current and frequency values, and allows good performance prediction ability. The multi-objective optimization process input are geometrical variables related to the motor electromagnetic configuration having direct impact on the output performance, is based on Genetic Algorithms (GA), and has been developed with the commercial software ModeFRONTIER®.

Pericardial effusion is a pathological accumulation of fluid within pericardial cavity, which may compress heart chambers with hemodynamic impairment. We sought to determine the mechanics underlying the physiology of the hemodynamic impairment due to pericardial effusion using patient-specific computational modeling. Computational models of left ventricle and right ventricle were based on magnetic resonance images obtained from patients with pericardial effusion and controls. Myocardial material parameters were adjusted, so that volumes of ventricular chambers and pericardial effusion agreed with magnetic resonance imaging data. End-diastolic and end-systolic pressure–volume relationships as well as stroke volume were determined to evaluate impaired cardiac function of biventricular model. Distributions of myocardial fiber stresses and their regional variation along left ventricular wall were compared between patient groups. Both end-diastolic and end-systolic pressure–volume relationships shifted to the left for patients with pericardial effusion, with right ventricle diastolic filling particularly restricted. Left ventricle function as estimated by Starling curve was reduced by pericardial effusion. End-systolic fiber stress of left ventricle was significantly reduced as compared to that found for healthy patients. Myocardial stress was found increased at interventricular septum when compared to that exerted at lateral wall of left ventricle. Right ventricular myocardial stress was reduced as a consequence of the pressure equalization between right ventricle and pericardial effusion. Diastolic right ventricle collapse in patients with pericardial effusion is related to higher myocardial fiber stress on interventricular septum and to an extensible pericardium reducing motion of ventricular chambers, with right ventricle particularly restrained. These findings likely portend progression of pericardial effusion to cardiac tamponade.

In this paper, a new semi-automatic procedure to transform three-dimensional point clouds of complex objects to three-dimensional finite element models is presented and validated. The procedure conceives of the point cloud as a stacking of point sections. The complexity of the clouds is arbitrary, since the procedure is designed for terrestrial laser scanner surveys applied to buildings with irregular geometry, such as historical buildings. The procedure aims at solving the problems connected to the generation of finite element models of these complex structures by constructing a fine discretized geometry with a reduced amount of time and ready to be used with structural analysis. If the starting clouds represent the inner and outer surfaces of the structure, the resulting finite element model will accurately capture the whole three-dimensional structure, producing a complex solid made by voxel elements. A comparison analysis with a CAD-based model is carried out on a historical building damaged by a seismic event. The results indicate that the proposed procedure is effective and obtains comparable models in a shorter time, with an increased level of automation.

In this paper, we present a family of fluxgate magnetic sensors on printed circuit boards (PCBs), suitable for an electronic compass. This fabrication process is simple and inexpensive and uses commercially available thin ferromagnetic materials. We developed and analyzed the prototype sensors with software tools based on the finite-element method. We developed both single- and double-axis planar fluxgate magnetic sensors as well as front-end circuitry based on second-harmonic detection. Two amorphous magnetic materials, Vitrovac 6025X (25 mu m thick) and Vitrovac 6025Z (20 pm thick), were used as the ferromagnetic core. We found that the same structures can be made with Metglas ferromagnetic core. The double-axis fluxgate magnetic sensor has a sensitivity of about 1.25 mV/mu T with a linearity error of 1.5% full scale, which is suitable for detecting Earth's magnetic field (+/- 60 mu T full-scale) in an electronic compass

The aim of this work is to evaluate by numerical simulation the real stress state of a welded component subjected to a sinusoidal external load. In particular, the relaxation process of the residual stress, due to the application of a cyclic external load, has been studied. Longitudinal welded joints, laser welded and 3 mm thick, are analysed in this work following the residual stress evolution during a fatigue test. A numerical procedure, implemented by the ABAQUS code, carries out the residual stress field originated by a welding process and it is taken as a pre-stress condition in the present ABAQUS simulations. In order to evaluate the influence of the amplitude level on the residual stress relaxation, eight different sinusoidal loads at the load ratio R = 0.1 are applied to the model. The results show a significant reduction in the initial residual stress level, even after the first load cycle. They offer a very precise explanation of the fatigue behaviour of this kind of welded joints, confirming the behaviour experimentally observed.