Micro-scale Finite Element Models Research Articles

3D Computational Modeling of Blast Wave Transmission in Human Ear From External Ear to Cochlear Hair Cells: A Preliminary Study.

Auditory disabilities like tinnitus and hearing loss caused by exposure to blast overpressures are prevalent among military service members and veterans. The high-pressure fluctuations of blast waves induce hearing loss by injuring the tympanic membrane, ossicular chain, or sensory hair cells in the cochlea. The basilar membrane (BM) and organ of Corti (OC) behavior inside the cochlea during blast remain understudied. A computational finite element (FE) model of the full human ear was used by Bradshaw etal. (2023) to predict the motion of middle and inner ear tissues during blast exposure using a 3-chambered cochlea with Reissner's membrane and the BM. The inclusion of the OC in a blast transmission model would improve the model's anatomy and provide valuable insight into the inner ear response to blast exposure. This study developed a microscale FE model of the OC, including the OC sensory hair cells, membranes, and structural cells, connected to a macroscale model of the ear to form a comprehensive multiscale model of the human peripheral auditory system. There are 5 rows of hair cells in the model, each row containing 3 outer hair cells (OHCs) and the corresponding Deiters' cells and stereociliary hair bundles. BM displacement 16.75 mm from the base induced by a 31 kPa blast overpressure waveform was derived from the macroscale human ear model reported by Bradshaw etal. (2023) and applied as input to the center of the BM in the OC. The simulation was run for 2 ms as a structural analysis in ANSYS Mechanical. The FE model results reported the displacement and principal strain of the OHCs, reticular lamina, and stereociliary hair bundles during blast transmission. The movement of the BM caused the rest of the OC to deform significantly. The reticular lamina displacement and strain amplitudes were highest where it connected to the OHCs, indicating that injury to this part of the OC may be likely due to blast exposure. This microscale model is the first FE model of the OC to be connected to a macroscale model of the ear, forming a full multiscale ear model, and used to predict the OC's behavior under blast. Future work with this model will incorporate cochlear endolymphatic fluid, increase the number of OHC rows to 19 in total, and use the results of the model to reliably predict the sensorineural hearing loss resulting from blast exposure.

Elastic behaviour of bamboo at nano- and microscale

This paper presents an anatomy-based numerical multiscale approach for modelling the mechanical behaviour of Moso bamboo, addressing limitations in previous research where the intricate microstructure was often simplified. The mechanical response of bamboo culms is predicted at the nano and microscale considering the orthotropic behaviour of cellulose microfibrils in different layers of tissues, deviating from conventional isotropic assumptions. Through nano and microscale finite element models, the impact of chemical composition and microfibril angle on elastic properties of different layers of the fibre and parenchyma cells are explored at two different levels of moisture content. At low moisture content, fibres within vascular bundles exhibit significantly higher longitudinal and transverse elastic moduli compared to parenchyma cells. When the moisture content is high, the properties of the fibre and parenchyma cells are less different. Anisotropic behaviour at the nanoscale contributes to a more accurate prediction of the mechanical properties of bamboo culms at the microscale, particularly in the transverse direction in moist conditions. This study lays the groundwork for forthcoming research in modelling the mechanical behaviour of bamboo culm at meso and macroscales.

Assessment of bone ingrowth around beaded coated tibial implant for total ankle replacement using mechanoregulatory algorithm

The long-term performance of porous coated tibial implants for total ankle replacement (TAR) primarily depends on the extent of bone ingrowth at the bone-implant interface. Although attempts were made for primary fixation for immediate post-operative stability, no investigation was conducted on secondary fixation. The aim of this study is to assess bone ingrowth around the porous beaded coated tibial implant for TAR using a mechanoregulatory algorithm. A realistic macroscale finite element (FE) model of the implanted tibia was developed based on computer tomography (CT) data to assess implant-bone micromotions and coupled with microscale FE models of the implant-bone interface to predict bone ingrowth around tibial implant for TAR. The macroscale FE model was subjected to three near physiological loading conditions to evaluate the site-specific implant-bone micromotion, which were then incorporated into the corresponding microscale model to mimic the near physiological loading conditions. Results of the study demonstrated that the implant experienced tangential micromotion ranged from 0 to 71 μm with a mean of 3.871 μm. Tissue differentiation results revealed that bone ingrowth across the implant ranged from 44 to 96 %, with a mean of around 70 %. The average Young's modulus of the inter-bead tissue layer varied from 1444 to 4180 MPa around the different regions of the implant. The analysis postulates that when peak micromotion touches 30 μm around different regions of the implant, it leads to pronounced fibrous tissues on the implant surface. The highest amount of bone ingrowth was observed in the central regions, and poor bone ingrowth was seen in the anterior parts of the implant, which indicate improper osseointegration around this region. This macro-micro mechanical FE framework can be extended to improve the implant design to enhance the bone ingrowth and in future to develop porous lattice-structured implants to predict and enhance osseointegration around the implant.

Micromechanical damage analysis of Al-Al2O3 composites via cold-spray additive manufacturing

3D micro-scale finite element (FE) models were developed to analyze the stress-state-dependent initiation and growth of failure of cold-sprayed additively manufactured (CSAM) Al-Al2O3 composites. Informed by experimental particle size distributions and porosity measurements, representative volume elements (RVEs) were generated by Digimat. Stress-state-dependent constitutive models for the Al matrix and Al2O3 ceramic particles were implemented by VUMAT subroutines in ABAQUS/Explicit FE solver. For the first time in the literature on metal–ceramic composites, the microscale failure mechanisms involving matrix ductile failure, particle cracking, and matrix/particle debonding were all quantified based on the crack volume fraction, the fraction of cracked particles, and the fraction of fully debonded interfacial nodes, respectively. The FE model was quantitatively and qualitatively validated by the experimental data for Al-46 wt% Al2O3 under quasi-static uniaxial compression. The validated model was used to investigate the effect of the particle content and size on the material behavior subjected to different stress states. The results revealed that the failure mechanisms are activated in a specified order across different stress states: I. matrix/particle debonding, II. particle cracking, and III. matrix ductile failure. The material ductility observed under compression/shear vanishes under tension due to the earlier activation of debonding and the faster growth (∼ 10 times) of the particle cracking mechanism. Additionally, it was shown that the particle size minimally affects the material strength and flow stress under shear which is likely related to the low load transfer effect through the interfaces. The novelty of this work stems from the provision of a better understanding of the stress-state-dependent evolution of failure mechanisms through a systematic quantification framework whose outcomes have implications for the design of better-performing Al-Al2O3 composites via control of the evolution of failure mechanisms and developing micromechanism-based constitutive models for CSAM metal–ceramic materials.

Relation Between Interface Geometry and Tensile Shear Strength of Ultrasonically Welded Joints

The reliable use of ultrasonic metal welding requires a thorough understanding of the relevant bonding mechanisms. This article presents an approach to systematically investigate the relation between the mechanical properties and the interface of selected Al/Cu and Al/GFRP joints. The hypothesis is that the microstructure and tensile shear strength of the specimen can be related to their interface properties presented by contact stiffness and damage initiation traction. For this purpose, the mentioned hybrid material systems were ultrasonically welded using specific parameters to achieve defined levels of mechanical joint strengths. Micro sections and fracture surfaces were characterized to identify the interface geometry at certain strength levels. The main findings were different shares of bonded areas in the interface and characteristic micro geometries. Microscale finite element models of representative samples were developed to determine the stress and deformation behavior in the interface under tensile shear load and to compare the influence of the interface geometry on contact conditions to a simplified model. The simulations provide information about the influence of different damage initiation tractions and geometrical characteristics in the joints’ interfaces, as well as their contribution to the overall joint strength. For prospective industrial applications, they can serve as basis for further development of a contact model on component scale.

Double diaphragm forming simulation for net-shape component using multi-layered biaxial non-crimp fabrics

Compared to autoclave-cured prepreg, liquid composite moulding (LCM) is a cost-effective alternative to produce advanced composites, thanks to the less-expensive intermediate materials, lower capital investment and shorter cycle time. A separate preforming step is typically required within the process chain to convert 2D fabric blanks into complex 3D geometries before moulding. Numerical models are therefore important to ensure near net-shape preforms during the design phase, in order to minimise the material wastage related to preforming. In this study, a microscale finite element (FE) model was employed to assist in determining the ply shape of multi-ply biaxial non-crimp fabrics (NCF) to achieve net-shape preforms made by double diaphragm forming (DDF) using a spar-like geometry. The forming deformation of the NCF was predicted by simulations considering the in-plane stiffness of the NCF. The location of wrinkles was indicated by the simulation using membrane elements. By continuously removing the redundant fabric material making contact with the machine bed and tool surface, net-shape preforms were achieved for the target geometry using single and multiple NCF plies respectively. Compared with the original ply shape, the number of wrinkles was reduced for the net-shape case due to the reduction in the bridging force induced by the contact pairing between fabric-diaphragm assembly and the machine bed.

Experimentally verified dual-scale modelling framework for predicting the strain rate-dependent nonlinear anisotropic deformation response of unidirectional non-crimp fabric composites

A new hierarchical dual-scale modelling framework is developed for predicting the strain rate-dependent nonlinear deformation response of a unidirectional non-crimp fabric (NCF) carbon fiber/snap-cure epoxy composite. A linear Drucker-Prager model that considers tension–compression asymmetry of the yield surface was used to capture the elastic–plastic response of the epoxy within the microscale finite element (FE) model, while randomly dispersed carbon fibers were treated as linear elastic. For the mesoscale FE model, the effective elastic–plastic response of the impregnated tow was modelled using Hill’s anisotropic yield function. The post-yield strain rate dependency of the epoxy and impregnated tow was captured with the Johnson-Cook model, with the former being calibrated using available experimental data. The predicted post-yield response of the impregnated tow was found to be dependent on the applied strain rate. An excellent agreement was observed between the predicted and experimentally measured stress–strain response for the NCF composite at quasi-static strain rates. The predicted in-plane and out-of-plane shear stress–strain responses revealed a strong dependence on the applied strain rate. The newly developed dual-scale modelling framework can be utilized as a tool to effectively predict the strain rate-dependent non-linear response for other fabric-reinforced composite material systems.

Multiscale numerical and experimental analysis of cooling-induced thermal shrinkage behaviors and residual stresses in 2.5D woven fiber/aluminum matrix composites

The cooling-induced thermal shrinkage behavior and residual stress in fabrication of 2.5D woven fiber reinforced Al composites were investigated by numerical and experimental approach. A microscale finite element (FE) model was established to determine the transversely isotropic thermal shrinkage of the Al-impregnated yarns. The validated properties were subsequently input into a mesoscale FE model for the composites, in which the temperature-dependent properties of the constituent materials were incorporated. Parallel experiments were carried out to verify the thermal shrinkage behaviors and the residual stresses that were predicted by the FE simulations. The residual stress distribution of the matrix pocket, warp and weft yarns were studied, and their contributions to the local damage of matrix pocket and interface were analyzed. Based on the verified model, the effect of fabric structure on the residual stresses and macroscopic shrinkage properties were parametrically evaluated. The results make a contribution to evaluating the cooling-induced residual stress, local damage, and shrinkage behavior of metal matrix composites reinforced with complex fabric.

A 3D micromechanics-based failure criterion for fiber reinforced composites under longitudinal compression

A novel micromechanics-based failure criterion for longitudinal compressive failure of fiber reinforced composites is proposed based on the cross-scale stress calculation formula. Two failure modes, fiber bending failure and inter-fiber shear failure, are considered in the failure criterion, judged by the micro-scale stress inner fiber and inter fiber, respectively. The validity of the failure criterion on predicting strength and failure mode is proved by micro-scale finite element models and the existing experimental results. Final, the key effect parameters of longitudinal compressive strength are discussed. The proposed failure criterion can be used for composite structures simulation and composite materials performance design.

Microscale damage modeling of bolt-hole contact interface during the bolt installation process of composite structure

During the interference-fit joining process of composite bolted structure, the bolt-hole contact interface would form naturally. Understanding the microscale damage mechanism of bolt-hole contact interface is crucial for guarantying load bearing and sealing performance of the composite bolted structure. In this paper, a microscale finite element model was proposed to model the damage behaviors of the bolt-hole contact interface during the bolt installation process. The micro rough characteristics of composite hole-wall surface, bolt surface and bolt coatings were explicitly considered and modeled. The damage initiation of the composites and bolt (including coatings) were calculated by the modified 3D Hashin criterion and von Mises criterion. The proposed microscale model was validated by comparing the load–displacement curve and damage modes with experiments. The results show that the damages primarily occur on the composite hole-wall and bolt coatings. The damage of coatings is primary caused by the squeezing and friction. The damage ratio of coatings is approximately linear positive related to the interference-fit size. The proposed microscale model not only has the potential application for the prediction of microscopic damage, but also for the formation of leakage channel and the protection of corrosion location.

Simplified mechanical models for the seismic collapse performance prediction of unreinforced masonry structures

Unreinforced masonry, including non-confined unreinforced masonry (NCURM) and confined unreinforced masonry (CURM), constitutes a significant portion of low-rise buildings and is prone to collapse due to high seismic vulnerability. Seismic collapse performance prediction is an effective method to reduce structural collapse, and it requires the analytical model that can correctly simulate structural mechanical behaviors, especially for the deterioration behaviors from accumulation damage. Macro-scale structural models constructed based on hysteretic models of walls have small computational efforts compared to micro-scale finite element models, and are preferred for structural seismic collapse performance analysis. However, existing hysteretic models of NCURM wall and CURM wall lack accuracy in considering the deterioration behaviors due to incorrect model forms or lack of available model parameter values. In this study, an experimental database consisting of cyclic tests on 47 NCURM walls and 50 CURM walls is assembled based on the existing literature. The hysteretic models of NCURM wall and CURM wall are developed by the combined use of the assembled database and the Ibarra-Krawinkler (IK) model from Ibarra et al. The IK model has versatile consideration of the in-cycle and cyclic deterioration behaviors and is used for the modeling of walls. A calibration procedure that clearly distinguishes the in-cycle and cyclic deterioration behaviors is established, and the model parameters of test walls in the database are calibrated. By regression analyses of calibration results, a set of empirical equations are created for determining model parameters. To satisfy the seismic collapse performance analysis of regional masonry buildings, the multi-degree-of-freedom (MDOF) shear model of masonry structure is further given based on the wall hysteretic model, which is constructed by the structural inter-story mechanical behaviors and has very small computational efforts. Good accuracy of both wall hysteretic model and structural MDOF shear model is verified by the comparisons with experimental and numerical results.

Cell-Laden Alginate Hydrogel Modelling using Three-Dimensional (3D) Microscale Finite Element Technique

A novel modelling technique using finite element analysis to mimic the mechanoresponse of cell-laden biomaterial is proposed for the use in bioinks and other tissue engineering applications. Here, a hydrogel-based composite biomaterial specimen was used consisting of 5% (V/V) HeLa cells added to alginate solution (4% W/V) and another specimen with no living cell present in alginate solution (4% W/V). Tensile test experiments were performed on both the specimens with a load cell of 25 N. The specimens were bioprinted using an in-house developed three-dimensional (3D) bioprinter. To allow for the nonlinear hyperelastic behaviour of the specimen, the specimens were loaded very slowly, at rates of 0.1 mm/min and 0.5 mm/min, during the tensile test, respectively. The microscale finite element models developed in ANSYS were loaded with similar load rates and their responses were recorded. Both the model results were validated with the experiment results. A very good agreement between the finite element model and the tensile test experiment was observed under the same mechanical stimuli. Hence, the study reveals that cell-seeded bioprinted scaffold can be virtually modelled to obtain its mechanical characteristics beforehand.

Shear testing and failure modelling of calcium phosphate coated AZ31 magnesium alloys for orthopaedic applications

Magnesium orthopaedic fracture fixation devices can potentially provide significant clinical benefits, such as the elimination of secondary surgeries for device removal due to in-vivo resorption and reduced stress shielding due to reduced device stiffness. However, development, approval, and clinical adoption of magnesium devices has been hindered by the excessively high rates of in-vivo corrosion such that the structural integrity of the device can be catastrophically reduced before fracture healing occurs. Coating of devices with calcium phosphate coatings has been shown to significantly reduce corrosion rates, while enhancing osseointegration. However, the adhesion strength between the CaP coatings and magnesium substrates has not been previously investigated. Clinical insertion of fracture fixation devices such as intramedullary nails and k-wires will impose significant shear loading on the coated surface of the implant. If the effective shear strength of the coating-device interface is not sufficiently high, the coating will be damaged and removed during device insertion. In the current study a bespoke experimental-computational approach is developed to provide a new understanding of the relationship between coating thickness, surface roughness, and effective shear strength of the CaP coating- Mg substrate interface. Nine test cases were created by adjusting either the deposition time (3 thickness values) or the surface treatment of the Mg alloy using SiC paper (3 roughness values) and double-lap shear testing was performed for these coating configurations. Strain development in the Mg substrates was monitored using strain gauges, and failure stress was determined for each configuration. Test results revealed that the effective shear strength of the coating-substrate interface is significantly higher for coatings on the rougher substrate surfaces when compared to those on smoother surfaces. Coating thickness was not found to significantly influence the effective shear strength over the range considered in this study (0.37–1.34 μm). Micro-scale finite element models of lap-shear tests were constructed using experimental profilometry data. Simulations of rough coating-substrate interfaces reveal that significant localised compression occurs at the coating-substrate interface in regions of large asperities. A novel cohesive zone formulation has been developed to simulate compression induced shear hardening, and the resultant simulations are found to accurately predict the significantly higher effective shear strength measured experimentally for rougher coatings compared to smoother Mg substrate surfaces.

Prediction of air permeability coefficient and water-vapor resistance of 3D textile layer

This study presents a computational model for investigation of the air permeability coefficient and water-vapor resistance coefficient through 3D textile layer. The effective values of the coefficients are highly dependent on the volumetric internal structure of the layer. The computational study of air and water vapor flow has been performed a microscale finite element model of the representative volume of the textile layer by taking into account the real configuration the yarns and filaments. The effective values of the coefficients were obtained by using taking average values of air and water vapor fluxes through the thickness of the representative volume. The steady state computational models in micro scale are based on Navier-Stokes and Brinkman partial differential equations. The simulations were performed in Comsol Multiphysics 5.3a software environment by using laminar flow (.spf) application mode. Numerical results for the air permeability of the samples were obtained, analyzed and validated by comparing against experimental data. Good agreement with experimental data has been achieved. Highlights COMSOL software was used to simulate air permeability and water-vapor resistance of 3D textile layer. The numerical model has demonstrated its efficiency comparing with experimental air permeability measurements.

Review of compatibility between SANS 10400 deemed-to-satisfy masonry wall provisions and loading code

South Africa has a housing shortage estimated in excess of 2 million units. This backlog is being addressed predominantly with the construction of 40 m2 low-income, single-storey, detached, state-subsidised houses built with conventional concrete masonry units, regulated by the Application of the National Building Regulations, SANS 10400. However, several developments warrant a reconsideration of SANS 10400 deemed-to-satisfy masonry wall provisions. Two critical configurations of single-storey, unreinforced, bonded masonry walls are generated, based on these deemed-to-satisfy provisions. Subsequently, a simplified micro-scale finite element model is used to analyse these configurations under serviceability and ultimate limit state loading conditions. Characterisation tests of the concrete masonry material, together with numerical fitting to test data and data taken from literature, generate the necessary parametric input. The numerical analyses reveal that in half of the load cases, the walls' resistances failed to achieve the design load as required by the South African loading code. A significant shortfall was found for the out-of-plane resistance against the wind load, as well as structural vulnerability under seismic loading due to the geometric layout permitted by the deemed-to-satisfy rules. This indicates that the SANS 10400 provisions for masonry wall panel geometries require reconsideration, especially given the recent revision of the South African loading code.

A multiscale framework for predicting the mechanical properties of unidirectional non-crimp fabric composites with manufacturing induced defects

The aim of this study was to evaluate the effect of manufacturing induced in-plane tow misalignment and out-of-plane tow crimp on the mechanical properties of a heavy-tow unidirectional non-crimp fabric (UD-NCF) composite. The elastic constants and failure onset (strength) are predicted by employing a multiscale computational approach. Micro-scale finite element (FE) models that explicitly represent the fibers and matrix within the tow microstructure were used to predict the effective properties of the tow. Meso-scale FE models comprised of the homogenized tows and surrounding matrix were used to predict the properties of a UD NCF composite lamina. Four meso-scale models, identified as ideal, crimp, misalignment and real, were considered in this study. No manufacturing defects were represented in the ideal model, while out-of-plane crimp, in-plane misalignment and both out-of-plane crimp and in-plane misalignment were accounted for in the crimp model, misalignment model and real model, respectively. Predicted lamina stiffness based on the real model are found to be in an excellent agreement with available experimental data, which was not always the case for the other three models. The longitudinal and transverse strength predictions are found to be dependent on the chosen local failure criteria for each model. Max-stress and Puck’s fiber failure criteria provide an excellent estimate of longitudinal strength while the Puck’s inter-fiber failure and Tsai-Hill criteria predict transverse strength with good accuracy. The feasibility to accurately predict the mechanical properties of heavy tow non-crimp fabric composites by incorporating their inherent micro-structural defects is demonstrated in this study.

Fiber/matrix interface stress analysis of flax-fiber composites under transverse loading considering material nonlinearity

Distribution of stresses in fiber/matrix interface in UD flax fiber reinforced composites is investigated under transverse loading and compared with conventional synthetic fibers. Micro-scale finite element models with representative volume elements are generated with various fiber packing types and fiber volume ratios. The study is performed for various strain values, which take into account the material nonlinearity of matrix. The results show that significantly lower stress concentrations exist in the case of flax fibers compared to glass fiber composites, explaining the absence of transverse cracks until failure in previously conducted transverse tension tests. Increase in the applied transverse strain causes a further decrease in the stress concentrations due to the nonlinear behavior of the matrix.

A multiscale description of bond formation in cold roll bonding considering periodic cracking of thin surface films

The bond strength evolution in a roll bonding process is commonly described by means of the so-called “film theory” which explains the most important mechanisms associated with the joining by plastic deformation. Inspired by this theory, a multiscale finite element model is presented in this paper with the aim to describe the bond formation between similar metals in a cold roll bonding process. To achieve this goal, the joining of metal sheets in a rolling process is modeled by considering three different geometrical scales. First, a macroscale finite element model is developed to assess the distribution of stresses and strains along the joint interface in a rolling process. Then, a mesoscale finite element model for the joint interface is presented. The mesoscale model accounts for the periodic cracking of thin brittle surface films existing on the top of the metallic layers. This model is also used to determine a proper size for the microscale unit cell model of bonding. Finally, the focus lies on a microscale finite element model which describes the most important micromechanisms taking place during cold welding. This model is then employed to evaluate the bond strength value between the rolled metallic layers. It is shown that the model is able to provide a good description for the bond strength evolution. In addition, the effects of influencing factors on the bonding, such as the degree of plastic deformation, the thickness and the material properties of surface films are numerically investigated.

Numerical simulation of periodic cracking mechanism in microscopic surface films during roll bonding processes

AbstractThe microscopic surface films existing on the top of metallic layers play an important role in the process of joining by plastic deformation. The bond formation during cold welding processes is basically associated with the fracturing of surface films to produce intimate metallic contacts. The present paper aims at providing a numerical model to describe the cracking pattern of brittle surface films bonded to the ductile substrates. A microscale finite element model is developed which takes into account the fracturing mechanisms of thin surface films in roll bonding processes. The presented model is calibrated by using the existing experimental data for an aluminum alloy covered by a thin layer of oxide film. The model is also validated against a well‐known analytical model for periodic cracking. The distribution of stresses within the fractured surface film demonstrates that the generated cracks in the surface film have essentially a periodic pattern. Moreover, it is shown that the crack spacing is highly dependent on the properties of the surface film. Finally, the obtained results for the roll bonding show that a crack density saturation takes place at the entry of the roll bite where a small surface expansion is applied to the rolled samples.

Linking microvascular collapse to tissue hypoxia in a multiscale model of pressure ulcer initiation.

Pressure ulcers are devastating injuries that disproportionately affect the older adult population. The initiating factor of pressure ulcers is local ischemia, or lack of perfusion at the microvascular level, following tissue compression against bony prominences. In turn, lack of blood flow leads to a drop in oxygen concentration, i.e, hypoxia, that ultimately leads to cell death, tissue necrosis, and disruption of tissue continuity. Despite our qualitative understanding of the initiating mechanisms of pressure ulcers, we are lacking quantitative knowledge of the relationship between applied pressure, skin mechanical properties as well as structure, and tissue hypoxia. This gap in our understanding is, at least in part, due to the limitations of current imaging technologies that cannot simultaneously image the microvascular architecture, while quantifying tissue deformation. We overcome this limitation in our work by combining realistic microvascular geometries with appropriate mechanical constitutive models into a microscale finite element model of the skin. By solving boundary value problems on a representative volume element via the finite element method, we can predict blood volume fractions in response to physiological skin loading conditions (i.e., shear and compression). We then use blood volume fraction as a homogenized variable to couple tissue-level skin mechanics to an oxygen diffusion model. With our model, we find that moderate levels of pressure applied to the outer skin surface lead to oxygen concentration contours indicative of tissue hypoxia. For instance, we show that applying a pressure of 60kPa at the skin surface leads to a decrease in oxygen partial pressure from a physiological value of 65mmHg to a hypoxic level of 31mmHg. Additionally, we explore the sensitivity of local oxygen concentration to skin thickness and tissue stiffness, two age-related skin parameters. We find that, for a given pressure, oxygen concentration decreases with decreasing skin thickness and skin stiffness. Future work will include rigorous calibration and validation of this model, which may render our work an important tool toward developing better prevention and treatment tools for pressure ulcers specifically targeted toward the older adult patient population.