Elastic Distribution Research Articles

The elasticity distribution of under-band based on pressure comfort and breast support performance for seamless sports bras

Seamless knitted sports bra is becoming popular for its high performance in tactility and pressure comfort, however, it also encounters the problem of insufficient support. To improve the support performance, it is always knitted with strong elastic material in a reduced size than the body dimension, which will generate much pressure on the body, leading to discomfort. As the pressure distribution may affect the pressure comfort and support performance of the sports bra, this study aimed to explore novel information in optimizing the pressure comfort and support performance by applying elasticity distribution. 4 sports bras with different elasticity distribution on the under-band were developed to compare with the one without elasticity distribution, and 12 healthy women were involved as subjects. The pressure distribution and pressure comfort sensations both in static and dynamic conditions, and the reduction of breast displacement (RBD) of 5 sports bras were measured and analysed by ANOVA analysis. The results indicated that the pressure distribution, the pressure comfort and RBD were effectively changed by elasticity distribution. Bra D with a high Young’s modulus on the side area of the under-band was ideal and typical both in pressure comfort and RBD.

OC-071 Biomechanical Causes for Failure of The Physiomesh/Securestrap System. Experimental study

Abstract Introduction Physiomesh/Securestrap system entered market in 2013 and despite its producer assurence it become a spectacular disaster, eliminating Ethicon from market and resulting in multi-milion dollar lawsuits. The biological reasons for faileure of the Physiomesh implant were partly explained in animal models. However conlusions suggested that apart from biological components failure of Physiomesh/Securestrap was mainly due to biomechanical factors. Aim Based on above assumptions we assembled a multidisciplinary team to examine the biomechanical reasons of failure of Physiomesh/Securestrap system. Material and Methods Three kinds of experiments were performed with the use of porcine model to conclude on the reasons of system failure in the natural conditions: uni-axial test of mesh samples, determination of the mesh-tissue junction force limit and mesh-staples-tissue model behaviour under high “intra-abdominal” pressure load. Results Main reason for failure of Physiomesh/Securestrap is its primary concept. Building a mathematical model describing the forces acting on the implant anchored to anterior abdominal wall demonstrated that mesh lacked proper distribution of elasticity. Despite promising preclinical studies on the rabbit and porcine model, our experiment showed that it cannot me directly translated into humans. Conclusions The results of research on the cause and mechanism of failure of the Physiomesh/Securestrap system allow to draw conclusions to avoid similar errors in the future. The findings not only to expose the cause for the failure of Physiomesh/Securestrap, but also allow to better understand the forces acting within the abdominal cavity. Optimally, this will prevent similar situations from arising in the future.

Application of Classified Elastic Waves for AE Source Localization Based on Self-Organizing Map

Acoustic emission (AE) source localization has been used to visualize progress failures generated in a wide variety of materials. In the conventional approaches, AE source localization algorithms assume that the AE signal is propagated as a straight line. However, it is supposed that progress failures form heterogeneity of elastic wave velocity distributions. Hence, with the conventional source localization, it is expected that the localization accuracy is reduced in heterogeneous materials since diffraction and refraction waves are generated. Thus, if the straight propagation waves are classified, conventional source localizations are performed in the heterogeneous materials. The self-organizing map (SOM) is one of the unsupervised learning methods, and the SOM has potential to classify straight propagation waves for the source localizations. However, the application of classified AE signals in source localization is not popular. If classified AE signals are applied to the time difference of arrival (TDOA) method, which is the popular localization method, it is expected that number of visualized sources are decreased because the algorithm does not consider the selection of the propagated wave. Although ray tracing has potential to localize a larger number of sources than the TDOA method, it is expected that the localized sources are less accurate in comparison with results of the TDOA method. In this study, classified waves were applied to two of the source localizations, and model tests based on pencil-lead breaks (PLBs) generating artificial AE sources were conducted to validate the performance of the source localizations with classified waves. The results of the validation confirmed that the maximum error in the TDOA method is larger in comparison with ray tracing conducted with 20 mm intervals of source candidates. Moreover, ray tracing localizes the same number of sources as the number of PLB tests. Therefore, ray tracing is expected to more practically localize AE sources than the TDOA method if classified waves are applied.

Mechanical Behavior and Low-Cycle Fatigue Performance of a Carburized Steel for GTF Engines

Using nanoindentation technology to analyze the hardness and elastic modulus distributions of the local microzones within materials, it can be determined that the case-carburized specimen is a composite of the carburized case and the pseudo-carburized material in the core. The overall mechanical behavior of the case-carburized material is much closer to that of the completely carburized material, indicating that the carburized case dominates the case-carburized material. Stress fatigue tests conducted on carburized tubular specimens, pseudo-carburized solid specimens, and case-carburized solid specimens showed that the fatigue performance of the completely carburized material is slightly lower than that of the pseudo-carburized specimens due to lower plasticity. However, the fatigue performance of the case-carburized specimens is significantly better than that of the two homogeneous materials. This could be attributed to the graded material behavior and the larger compressive residual stress in the carburized case, which are the primary positive factors for improving the fatigue life of case-carburized materials. SEM fractographs revealed that the fatigue nucleation in the case-carburized specimen initiates from the transition zone rather than from the surface of the specimens as observed in the homogeneous materials. Low-cycle fatigue evaluation of ultra-high-power gear transmission systems should focus on the influences of the carburized case.

Experimental studies suggest differences in the distribution of thorax elasticity between insects with synchronous and asynchronous musculature.

Insects have developed diverse flight actuation mechanisms, including synchronous and asynchronous musculature. Indirect actuation, used by insects with both synchronous and asynchronous musculature, transforms thorax exoskeletal deformation into wing rotation. Though thorax deformation is often attributed exclusively to muscle tension, the inertial and aerodynamic forces generated by the flapping wings may also contribute. In this study, a tethered flight experiment was used to simultaneously measure thorax deformation and the inertial/aerodynamic forces acting on the thorax generated by the flapping wing. Compared to insects with synchronous musculature, insects with asynchronous muscle deformed their thorax 60% less relative to their thorax diameter and their wings generated 2.8 times greater forces relative to their body weight. In a second experiment, dorsalventral thorax stiffness was measured across species. Accounting for weight and size, the asynchronous thorax was on average 3.8 times stiffer than the synchronous thorax in the dorsalventral direction. Differences in thorax stiffness and forces acting at the wing hinge led us to hypothesize about differing roles of series and parallel elasticity in the thoraxes of insects with synchronous and asynchronous musculature. Specifically, wing hinge elasticity may contribute more to wing motion in insects with asynchronous musculature than in those with synchronous musculature.

Elastic Deformations Distribution in Laterally Bent Conical Nanowires

Elastic Deformations Distribution in Laterally Bent Conical Nanowires

An elastic–viscoplastic model with non-affine deformation and rotation of a distribution of embedded fibres

A large deformation continuum model for an elastically isotropic visco-plastic matrix reinforced by a distribution of fibres has been formulated. The fibre distribution is a symmetric positive-definite tensor with unit trace that is determined by an evolution equation. This evolution equation includes a competition between tendencies for affine evolution of the distribution and non-affine evolution causing the distribution to align with the elastic distortional deformation tensor or to become isotropic. Two elastic deformation measures are introduced associated with the fibre distribution. Specifically, non-affine measures of elastic distribution stretch and non-coaxiality of the distribution cause anisotropic stress response. The resulting model describes a number of effects relevant to growth and remodelling of biological tissues as well as to additive manufacturing of artificial materials. For example, the equations model the smooth transition from isotropic to anisotropic response seen in many biological tissues.

Facies‐constrained transdimensional amplitude versus angle inversion using machine learning assisted priors

ABSTRACTWe present a methodology for seismic inversion that generates high‐resolution models of facies and elastic properties from pre‐stack data. Our inversion algorithm uses a transdimensional approach where, in addition to the layer properties, the number of layers is treated as unknown. In other words, the data itself determine the correct model parameterization, that is, the number of layers. The reversible jump Markov Chain Monte Carlo method is an effective tool to solve such transdimensional problems as it generates models of reservoir properties along with uncertainty estimates. However, current implementations of the reversible jump Markov Chain Monte Carlo algorithms do not account for the non‐Gaussian and multimodal nature of model parameters. The target elastic reservoir properties generally have multimodal and non‐parametric distribution at each location of the model. The number of modes is equal to the number of facies. Taking these factors into account, we extend the reversible jump Markov Chain Monte Carlo algorithm to simultaneously invert for discrete facies and continuous elastic reservoir properties. The proposed extension to the algorithm iteratively samples the facies, by moving from one mode to another, and elastic properties by sampling within the same mode. The integration of facies classification within the inversion reduces non‐uniqueness, improves convergence speed and produces geologically consistent results. The workflow uses machine learning to generate probabilistic priors for the model parameters. We validate our approach by applying it to a synthetic dataset generated from a well log with two facies and then to a complex synthetic two‐dimensional model involving three facies having overlapping elastic property distribution. Finally, we apply our algorithm to a field dataset acquired over an unconventional reservoir. Our algorithm demonstrates the usefulness of incorporating facies information in seismic inversion and also the feasibility of inverting for facies from seismic data.

Thermoacoustic response of polymethyl methacrylate composite shells reinforced by carbon nanotube resting on Winkler–Pasternak elastic foundation

This paper presented an analytical method for investigating the vibroacoustic response of polymethyl methacrylate composite shells reinforced by CNTs resting on an elastic foundation under thermal loading. This structure is submerged in a moving fluid and excited by an acoustics plane wave. The CNTs are assumed to have a graded distribution in the polymethyl methacrylate matrix. The properties of the CNTs are assumed to be temperature-dependent. Different types of CNTs distributions such as UD, X, V, and O are considered. The Winkler–Pasternak model is applied to describe the vibrational behavior of the elastic foundation. The equations of motion of the structure are based on Hamilton’s principle using the TSDT, considering the effects of shear and rotation. To validate the present analytical method, the obtained results are compared with those of other researchers. Next, the effects of various significant parameters such as elastic foundation, temperature gradient, CNTs distributions, and Mach number on the TL are studied. The results show increasing the temperature reduces the TL because the stiffness bending of the structure decreases. It can be seen that the addition of CNTs to the matrix, with an appropriate volume fraction, improves the sound transmission loss due to the enhancement of stiffness.

Velocity dependent potential for alpha 40Ca-elastic scattering

Angular distribution of the differential cross section of α40Ca elastic scattering has been investigated in the anomalous large angle scattering (ALAS) region by a nonlocal velocity dependent optical potential with surface term. The geometrical potential parameters were fixed and the depths of the potential were determined by fitting elastic angular distribution over the energy range (23–53.9 MeV). The real and the imaginary parts of the optical potential used here are of Woods–Saxon form factors. An energy dependence of the potential depths has been investigated at fixed geometrical potential parameters.

Classification of Elastic Wave for Non-Destructive Inspections Based on Self-Organizing Map

An arrival time of an elastic wave is the important parameter to visualize the locations of the failures and/or elastic wave velocity distributions in the field of non-destructive testing (NDT). The arrival time detection is conducted generally using automatic picking algorithms in a measured time-history waveform. According to automatic picking algorithms, it is expected that the detected arrival time from low S/N signals has low accuracy if low S/N signals are measured in elastic wave measurements. Thus, in order to accurately detect the arrival time for NDT, the classification of measured elastic waves is required. However, the classification of elastic waves based on algorithms has not been extensively conducted. In this study, a classification method based on self-organizing maps (SOMs) is applied to classify the measured waves. SOMs visualize relation of measured data wherein the number of classes is unknown. Therefore, using SOM selects high and low S/N signals adequately from the measured waves. SOM is validated on model tests using the pencil lead breaks (PLBs), and it was confirmed that SOM successfully visualize the classes consisted of high S/N signal. Moreover, classified high S/N signals were applied to the source localization and it was noteworthy that localized sources were more accurate in comparison with using all of the measured waves.

The Mechanical Nature of the Lithosphere Beneath the Eastern Central Atlantic Hotspots

AbstractThe Eastern Central Atlantic (ECA) region includes the Azores, Canary, Cape Verde, Great Meteor, and Madeira hotspots. These hotspots exhibit a large variety of characteristics and are rooted in the lithosphere ranging in age from newly created at the Mid Atlantic Ridge to Jurassic at the NW Africa Atlantic margin. Therefore, the ECA region represents an excellent scenario to investigate in an integrated way the effects of hotspots on the mechanical structure of oceanic lithosphere. Here, we calculate the effective elastic thickness (Te) of the lithosphere from an analysis of gravity and topography. Azores hotspot is characterized by a Te < 10 km, whereas the Great Meteor, Cape Verde, and Madeira hotspots have intermediate Te (15–30 km) values. In contrast, the Canary hotspot is characterized by a much higher Te (>50 km), forming the largest and most prominent mechanical feature in the ECA. All the hotspots except Canary show standard elastic thickness values when compared to average values for the same age lithosphere and to other oceanic areas in the world. The high strength of the Canary hotspot may be related to the highly depleted mantle composition in the area. The comparison between the elastic thickness distribution and the upper mantle seismic velocity structure shows no correlation between the Te estimated at the ECA hotspots (with the exception of Azores) and the presence of low shear‐wave velocity anomalies in the underlying mantle. This lack of correlation suggests a negligible effect of upper mantle temperature anomalies on the flexure of the ECA region.

Analysis of nucleon-nucleus scattering data using a density-dependent semi-microscopic optical model with channel coupling

Background: The neutron scattering data was previously analyzed using a semi-microscopic optical model with channel coupling to inelastic excited states [Phys. Rev. C 100, 014603 (2019)]. The real part of the potential was constructed by single folding the density-independent M3Y-Paris bare nucleon-nucleon ($NN$) interaction, with zero-range knock-on exchange term, over the density of the target nucleus. The model reproduced the overall features of the inelastic angular distributions and polarization data. The elastic angular distributions were well reproduced.Purpose: In this work we test the effectiveness of the semi-microscopic optical model with channel coupling, but we employ a density-dependent BDM3Y1-Paris bare ($NN$) interaction, with the finite-range form of the knock-on exchange term, in describing the scattering observables, particularly, the inelastic distributions and polarization data.Method: The real volume term of the semi-microscopic model is constructed by single folding the density-dependent BDM3Y1-Paris bare ($NN$) interaction, over the matter distribution of the target nucleus. The ground state is coupled to low-lying inelastic excitation levels. The potential parameters are determined by fitting the elastic, inelastic, and polarization data corresponding to nucleon scattering off a wide range of mass numbers in the range $7\ensuremath{\le}A\ensuremath{\le}208$ for various energies from 10--95 MeV.Results: The density-dependent model resulted in significant improvements in the description of the inelastic angular distributions and analyzing power. In addition, the potential depths showed systematic linear dependence on incident energy, and one set of geometrical parameters is obtained for each nuclear target. We used our best-fit potential parameters to calculate the total cross sections corresponding to nucleon scattering off the considered nuclei. The calculated cross sections are in good agreement with the measured data.Conclusions: In a semi-microscopic optical model, construction of the real volume term by single folding the density-dependent BDM3Y1-Paris bare ($NN$) interaction, with finite form of the knock-on exchange term, results in significant improvements in reproducing the inelastic angular distributions and polarization data as compared to the case of using the density-independent M3Y-Paris bare nucleon-nucleon ($NN$) interaction, with either zero-range or finite-range exchange term.

A hybrid model to simulate the trench effect on the fatigue analysis of steel catenary risers in the touchdown zone

The gradual trench formation of steel catenary risers (SCRs) in the touchdown zone is known to significantly affect the SCR’s fatigue life. However, there is still no coherent agreement among researchers on the beneficial or detrimental effects of the trench on fatigue. Recent studies have shown that a potential source of contradictory fatigue results could be the methodology to incorporate the trench in the numerical simulations. Since the predefined mathematical trench profiles create non-realistic contact pressure hot spots in the seabed, and the nonlinear hysteretic seabed interaction models may cause premature trench stabilization, both methods distort the damage distribution. To resolve these problems, a new model called the Hybrid Trench Model (HTM) has been developed in this study by combining the linear soil stiffness and nonlinear hysteretic seabed interaction model. This hybrid model provides an equivalent stiffness distribution in the touchdown zone to simulate the trench profile obtained from a nonlinear riser–seabed interaction model. HTM’s capability in developing deep trenches, e.g., 5D, was examined along with perfect compatibility with the natural catenary shape of the riser, exhibiting the reliability of this method to incorporate the trench effect into the fatigue analysis.

Point-to-point optical coherence elastography using a novel phase velocity method

Optical coherence elastography (OCE) offers great promise for clinical application, however, its method for measuring elastic wave velocity has already become a big obstacle to further development. Here we proposed a novel phase velocity method, by which elastic wave velocity and Young's modulus of each position in a sample were obtained for the first time. More importantly, based on the one-to-one correspondence between position and Young's modulus, the Young's modulus values were directly mapped to the corresponding structure to achieve two-dimensional elasticity distribution image, where tiny differences in biomechanical properties within and between any regions-of-interest could be precisely identified. Our method realizes the first point-to-point OCE imaging that enables us to read and compare elasticity information directly from tissue structure, which may be convenient to make effective clinical judgements and thus improve the clinical translation of OCE.

Development of a New Response Spectrum Analysis Approach for Determining Elastic Shear Demands on Shear-Dominated Steel Building Frames

This research is focused on improving the conventional response spectrum analysis (CRSA) method for the elastic shear demands estimation of shear-dominated steel building frames. An alternative approach named the improved response spectrum analysis (IRSA) method is proposed and validated in this paper. A simplified procedure to capture the dynamic features of a continuous shear beam (CSB) with stepped stiffness is first presented, and then validated. The CSB is employed in IRSA to replace the original eigenvalue analysis in CRSA to provide the modal parameter estimation for the considered system. A modified SRSS (MSRSS) mode superposition based on a genetic algorithm is then proposed and employed in IRSA. Based on the analyses conducted in this research, it is found that using first three modes in MSRSS to execute mode superposition could provide a great estimation of the elastic shear demands distribution. The amplification of weighting coefficients for the second and third mode contribution indicates the underestimation of the high mode effect in CSRSS. Further, response history analyses (RHA) are performed on two demonstration building frames to evaluate the improvement of the IRSA. The results indicate that IRSA provides a more precise estimation on the elastic shear force demand distribution in shear-dominated steel building frames under seismic effects compared with that which was achieved by CRSA.

Ultrasound elasticity reconstruction with inaccurate forward model using integrated data-driven correction of data-fidelity gradient

Ultrasound elasticity images, which enable the visualization of quantitative maps of tissue stiffness, can be reconstructed by solving an inverse problem. Classical model-based approaches for ultrasound elastography use deterministic finite element methods (FEMs) to incorporate the governing physical laws leading to poor performance in low SNR conditions. Moreover, these approaches utilize approximate linear forward models discretized by FEMs to describe the underlying physics governed by partial differential equations (PDEs). To achieve highly accurate stiffness images, it is essential to compensate the error induced by noisy measurements and inaccurate forward models. In this regard, we propose a joint model-based and learning-based framework for estimating the elasticity distribution by solving a regularized optimization problem. To address noise, we introduce a statistical representation of the imaging system, which incorporates the noise statistics as a signal-dependent correlated noise model. Moreover, in order to compensate for the model errors, we introduce an explicit data-driven correction model, which can be integrated with any regularization term. This constrained optimization problem is solved using fixed-point gradient descent where the analytical gradient of the inaccurate data-fidelity term is corrected using a neural network, while regularization is achieved by data-driven unrolled regularization by denoising (RED). Both networks are jointly trained in an end-to-end manner.

Shear Stress Distribution in Double-lap Adhesive Joints Reinforced with Nylon Fabric: Numerical Investigation

Nowadays there are an increasing number of industrial fields in which adhesive technology finds application. The main reason for their growing interest in both science and production is due to the high structural efficiency of this type of joining. Numerous studies have investigated the stress distribution in the adhesive layer under unreinforced conditions. The present work analyzes the elastic shear stress distribution in double-lap adhesive joints between timber and float glass adherends, both in the classical configuration and with an introduction of a nylon reinforcement in the two-component (2K) structural epoxy adhesives layers. In particular, three geometric configurations were investigated: nylon placed on the inner adherend, outer adherend and both. The result showed how the presence of the nylon inclusion changes the stress distribution in the joint. Numerical modelling of the joints was carried out using FE ANSYS©19 software. The greatest reduction in peak adhesive stresses is achieved by placing the reinforcement at both interfaces of the adherends with the adhesives. In general, it can be observed that the insertion of the reinforcement layer leads to a reduction in peak shear stresses, resulting in a potential increase in the ultimate strength of the joint.

Study on elastohydrodynamic lubrication performance of double-layer composite water-lubricated bearings

Double-layer composite water-lubricated bearing is a new type of water-lubricated bearing which can integrate the good damping performance of low elastic under-layer bush and good tribological performance of plastic layer bush. This paper analyzes its elastohydrodynamic lubrication performance by fluid–structure interaction (FSI) method, and studies the effects of eccentricity ratio, rotational speed, elastic modulus distribution and thickness distribution of bearing bush on its lubrication performance. Results show that the lubrication performance of double-layer bearing is more like that of plastic bearing. As rotational speed and eccentricity ratio increase, the maximum water film pressure, the load carrying capacity and the maximum bush deformation increase significantly. As the elastic modulus of the low elastic under-layer bush decreases, the total bush deformation increases significantly, but the load carrying capacity decreases slightly. The bush thickness distribution influences the deformation distribution of both low elastic under-layer bush and plastic layer bush, but have little impact on the total bush deformation and bearing lubrication performance.

Stability Characteristics of Horizontal Wells in the Exploitation of Hydrate-Bearing Clayey-Silt Sediments

The mechanical properties of hydrate-bearing strata in clayey-silt sediments are significantly different from those of either conventional reservoirs or hydrate-bearing sandy sediments, which poses great challenges for wellbore stability analyses. The stability characteristics of a deviated borehole during drilling in hydrate-bearing clayey-silt sediments (HBS-CS) remain to be studied. In this paper, an analysis of the wellbore stability characteristics of a deviated borehole using the Mohr–Coulomb (M-C) criterion and Drucker–Prager (D-P) criterion was carried out based on the elastic stress distribution model of the surrounding strata of the wellbore and the triaxial shear tests of the HBS-CS. The results imply that the collapse pressure and safety density window are symmetrically distributed with deviation angle and azimuth. Considering the effect of hydrate decomposition, the collapse pressure gradient could become higher and the instability risks would be amplified. Considering the combined effects of collapse, fracture pressure gradient, and the safety density window, it is suggested that the borehole be arranged along an azimuth of 60–120°, which could greatly reduce the risk in a drilling operation.