Biomaterial Models Adjustment and Comparison for Ultra-High Molecular Weight Polyethylene in Finite Element Models

2018 ◽  
Author(s):  
Humberto Corro-Hernández ◽  
Agustín Vidal-Lesso ◽  
Elías Ledesma ◽  
Antonio de Jesús Balvantín-García
Keyword(s):  
Molecular Weight ◽  
Finite Element ◽  
High Molecular Weight ◽  
Numerical Solutions ◽  
Constant Strain Rate ◽  
Mechanical Tests ◽  
Isotropic Hardening ◽  
Load Curve ◽  
Prosthesis And Implants ◽  
Ultra High Molecular Weight

GUR1050 is a medical grade variety of ultra-high molecular weight polyethylene (UHMWPE) intended for use on total joint prosthesis and implants. Probes of this material were characterized on a compression test following ASTM norms and lineaments. Available data from these mechanical tests is fitted on multiple material models. Achieved results on numerical solutions of finite element modeling (FEM) of the tests are discussed, looking for the best one available in order to simulate with accuracy GUR1050 behavior, with specific interest on the load curve results, showing the pertinence of using certain models on different conditions. It was found that the use of a bilinear isotropic hardening model assures the best fit for GUR1050 behavior in uniaxial compression under a constant strain rate.

Derivation of the material models for ultra-high molecular-weight polyethylene fiber-reinforced armor-grade composites with different architectures

2016 ◽  
Vol 33 (3) ◽  
Author(s):  
Mica Grujicic ◽  
Jennifer Snipes ◽  
S. Ramaswami ◽  
Vasudeva Avuthu ◽  
Chian-Fong Yen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Design Methodology ◽  
Critical Role ◽  
Fiber Reinforcement ◽  
Mechanical Tests ◽  
Transverse Impact ◽  
Material Models ◽  
Polyethylene Fiber ◽  
Ultra High Molecular Weight

Purpose To overcome the problem of inferior through-the-thickness mechanical properties displayed by armor-grade composites based on 2-D reinforcement architectures, armor-grade composites based on 3D fiber-reinforcement architectures have recently been investigated experimentally. Design/methodology/approach The subject of the present work is armor-grade composite materials reinforced using ultra-high-molecular-weight polyethylene fibers and having four (two 2D and two 3D) prototypical architectures, as well as the derivation of the corresponding material models. The effect of the reinforcement architecture is accounted for by constructing the appropriate unit cells (within which the constituent materials and their morphologies are represented explicitly) and subjecting them to a series of virtual mechanical tests. The results obtained are used within a post-processing analysis to derive and parameterize the corresponding homogenized-material models. One of these models (specifically, the one for 0°/90° cross-collimated fiber architecture) was directly validated by comparing its predictions with the experimental counterparts. The other models are validated by examining their physical soundness and details of their predictions. Lastly, the models are integrated as user-material subroutines, and linked with a commercial finite-element package, in order to carry out a transient non-linear dynamics analysis of ballistic transverse impact of armor-grade composite-material panels with different reinforcement architectures. Findings It is found that the reinforcement architecture plays a critical role in the overall ballistic limit of the armor panel, as well as in its structural and damage/failure response. Originality/value To the authors’ knowledge, the present work is the first reported attempt to assess, computationally, the utility and effectiveness of 3D fiber-reinforcement architectures for ballistic impact applications.

Computational Analysis of Microstructure of Ultra High Molecular Weight Polyethylene for Total Joint Replacement

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Kelly M. Seymour ◽  
Sara A. Atwood
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Finite Element ◽  
Finite Element Model ◽  
High Molecular Weight ◽  
Element Model ◽  
Experimental Results ◽  
Linear Elastic ◽  
Ultra High Molecular Weight ◽  
Scanning Electron

Ultra high molecular weight polyethylene (UHMWPE, or ultra high), a frequently used material in orthopedic joint replacements, is often the cause of joint failure due to wear, fatigue, or fracture. These mechanical failures have been related to ultra high's strength and stiffness, and ultimately to the underlying microstructure, in previous experimental studies. Ultra high's semicrystalline microstructure consists of about 50% crystalline lamellae and 50% amorphous regions. Through common processing treatments, lamellar percentage and size can be altered, producing a range of mechanical responses. However, in the orthopedic field the basic material properties of the two microstructural phases are not typically studied independently, and their manipulation is not computationally optimized to produce desired mechanical properties. Therefore, the purpose of this study is to: (1) develop a 2D linear elastic finite element model of actual ultra high microstructure and fit the mechanical properties of the microstructural phases to experimental data and (2) systematically alter the dimensions of lamellae in the model to begin to explore optimizing the bulk stiffness while decreasing localized stress. The results show that a 2D finite element model can be built from a scanning electron micrograph of real ultra high lamellar microstructure, and that linear elastic constants can be fit to experimental results from those same ultra high formulations. Upon altering idealized lamellae dimensions, we found that bulk stiffness decreases as the width and length of lamellae increase. We also found that maximum localized Von Mises stress increases as the width of the lamellae decrease and as the length and aspect ratio of the lamellae increase. Our approach of combining finite element modeling based on scanning electron micrographs with experimental results from those same ultra high formulations and then using the models to computationally alter microstructural dimensions and properties could advance our understanding of how microstructure affects bulk mechanical properties. This advanced understanding could allow for the engineering of next-generation ultra high microstructures to optimize mechanical behavior and increase device longevity.

scholarly journals A New Approach Based on Glued Multi-Ultra High Molecular Weight Polyethylene Forms to Fabricate Bone Replacement Products

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2545
Author(s):  
Tarek Dayyoub ◽  
Aleksey Maksimkin ◽  
Fedor Senatov ◽  
Sergey Kaloshkin ◽  
Natalia Anisimova ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Phenol Formaldehyde ◽  
Peel Strength ◽  
Mechanical Tests ◽  
Cortical Layer ◽  
Compressive Yield Strength ◽  
Ene Reaction ◽  
Promising Development ◽  
Ultra High Molecular Weight

Three types of glue based on thiol-ene reaction, polyvinyl alcohol (PVA)/cellulose, and phenol formaldehyde were prepared and applied on modified ultra-high molecular weight polyethylene (UHMWPE) samples grafted by cellulose. In comparison with unmodified UHMWPE samples, T-peel tests on the modified and grafted UHMWPE films showed an increase in the peel strength values for the glues based on thiol-ene reaction, PVA/cellulose, and phenol formaldehyde by 40, 29, and 41 times, respectively. The maximum peel strength value of 0.62 Kg/cm was obtained for the glue based on phenol formaldehyde. Mechanical tests for the cylindrical multi-UHMWPE forms samples, made of porous UHMWPE as a trabecular layer and an armored layer (cortical layer) that consists of bulk and UHMWPE films, indicated an improvement in the mechanical properties of these samples for all glue types, as a result of the UHMWPE films existence and the increase in the number of their layers. The maximum compressive yield strength and compressive modulus values for the armored layer (bulk and six layers of the UHMWPE films using the glue based on thiol-ene reaction) were 44.1 MPa (an increase of 17%) and 1130 MPa (an increase of 36%), respectively, in comparison with one armored layer of bulk UHMWPE. A hemocompatibility test carried out on these glues clarified that the modified UHMWPE grafted by cellulose with glues based on PVA/cellulose and thiol-ene reaction were classified as biocompatible materials. These multi-UHMWPE forms composites can be considered a promising development for joint reconstruction.

scholarly journals Structure, processing and performance of ultra-high molecular weight polyethylene (IUPAC Technical Report). Part 3: deformation, wear and fracture

2020 ◽  
Vol 92 (9) ◽  
pp. 1503-1519
Author(s):  
Clive Bucknall ◽  
Volker Altstädt ◽  
Dietmar Auhl ◽  
Paul Buckley ◽  
Dirk Dijkstra ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Dominant Factor ◽  
Stress Strain ◽  
Entanglement Density ◽  
Wide Range ◽  
And Performance ◽  
Ultra High Molecular Weight

AbstractThree grades of polyethylene, with weight-average relative molar masses, ${\bar{M}}_{\text{W}}$, of approximately 0.6 × 106, 5 × 106, and 9 × 106, were supplied as compression mouldings by a leading manufacturer of ultra-high molecular weight polyethylene (UHMWPE). They were code-named PE06, PE5, and PE9, respectively. Specimens cut from these mouldings were subjected to a wide range of mechanical tests at 23 °C. In tensile tests, deformation was initially elastic and dominated by crystallinity, which was highest in PE06. Beyond the yield point, entanglement density became the dominant factor, and at 40 % strain, the rising stress–strain curves for PE5 and PE9 crossed the falling PE06 curve. Fracture occurred at strains above 150 %. Differences in stress–strain behaviour between PE5 and PE9 were relatively small. A similar pattern of behaviour was observed in wear tests; wear resistance showed a marked increase when ${\bar{M}}_{\text{W}}$ was raised from 0.6 × 106 to 5 × 106, but there was no further increase when it was raised to 9 × 106. It is concluded that the unexpected similarity in behaviour between PE5 and PE9 was due to incomplete consolidation during moulding, which led to deficiencies in entanglement at grain boundaries; they were clearly visible on the surfaces of both tensile and wear specimens. Fatigue crack growth in 10 mm thick specimens was so severely affected by inadequate consolidation that it forms the basis for a separate report – Part 4 in this series.

Customized surface-guided knee implant: Contact analysis and experimental test

2017 ◽  
Vol 232 (1) ◽  
pp. 90-100 ◽  
Author(s):  
Ida Khosravipour ◽  
Shabnam Pejhan ◽  
Yunhua Luo ◽  
Urs P Wyss
Keyword(s):  
Molecular Weight ◽  
Finite Element ◽  
High Molecular Weight ◽  
Contact Pressure ◽  
Element Analysis ◽  
Pressure Sensitive ◽  
Sensitive Film ◽  
Pressure Sensitive Film ◽  
Total Knee ◽  
Ultra High Molecular Weight

Contact pressure and stresses on the articulating surface of the tibial component of a total knee replacement are directly related to the joint contact forces and the contact area. These stresses can result in wear and fatigue damage of the ultra-high-molecular-weight polyethylene. Therefore, conducting stress analysis on a newly designed surface-guided knee implant is necessary to evaluate the design with respect to the polyethylene wear. Finite element modeling is used to analyze the design’s performance in level walking, stair ascending and squatting. Two different constitutive material models have been used for the tibia component to evaluate the effect of material properties on the stress distribution. The contact pressure results of the finite element analysis are compared with the results of contact pressure using pressure-sensitive film tests. In both analyses, the average contact pressure remains below the material limits of ultra-high-molecular-weight polyethylene insert. The peak von Mises stresses in 90° of flexion and 120° of flexion (squatting) are 16.28 and 29.55 MPa, respectively. All the peak stresses are less than the fatigue failure limit of ultra-high-molecular-weight polyethylene which is 32 MPa. The average contact pressure during 90° and 120° of flexion in squatting are 5.51 and 5.46 MPa according to finite element analysis and 5.67 and 8.14 MPa according to pressure-sensitive film experiment. Surface-guided knee implants are aimed to resolve the limitations in activities of daily living after total knee replacement by providing close to normal kinematics. The proposed knee implant model provides patterns of motion much closer to the natural target, especially as the knee flexes to higher degrees during squatting.

scholarly journals Effect of Borpolymer on Mechanical and Structural Parameters of Ultra-High Molecular Weight Polyethylene

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3398
Author(s):  
Sakhayana N. Danilova ◽  
Afanasy A. Dyakonov ◽  
Andrey P. Vasilev ◽  
Aitalina A. Okhlopkova ◽  
Aleksei G. Tuisov ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Polymer Composites ◽  
High Molecular Weight ◽  
Supramolecular Structure ◽  
Structural Parameters ◽  
Mechanical Tests ◽  
Structural Studies ◽  
Scanning Calorimetry ◽  
X Ray Crystallography ◽  
Ultra High Molecular Weight

The paper presents the results of studying the effect of borpolymer (BP) on the mechanical properties, structure, and thermodynamic parameters of ultra-high molecular weight polyethylene (UHMWPE). Changes in the mechanical characteristics of polymer composites material (PCM) are confirmed and complemented by structural studies. X-ray crystallography (XRC), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and infrared spectroscopy (IR) were used to study the melting point, morphology and composition of the filler, which corresponds to the composition and data of the certificate of the synthesized BP. Tensile and compressive mechanical tests were carried out in accordance with generally accepted standards (ASTM). It is shown that BP is an effective modifier for UHMWPE, contributing to a significant increase in the deformation and strength characteristics of the composite: tensile strength of PCM by 56%, elongation at break by 28% and compressive strength at 10% strain by 65% compared to the initial UHMWPE, due to intensive changes in the supramolecular structure of the matrix. Structural studies revealed that BP does not chemically interact with UHMWPE, but due to its high adhesion to the polymer, it acts as a reinforcing filler. SEM was used to establish the formation of a spherulite supramolecular structure of polymer composites.

Finite Element Model of Equal Channel Angular Extrusion of Ultra High Molecular Weight Polyethylene

2021 ◽  
pp. 1-30
Author(s):  
Kostiantyn Vasylevskyi ◽  
Igor Tsukrov ◽  
Kateryna Miroshnichenko ◽  
Stanislav Buklovskyi ◽  
Hannah Grover ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Finite Element ◽  
Shear Strain ◽  
High Molecular Weight ◽  
Equal Channel Angular Extrusion ◽  
Dead Zone ◽  
Extrusion Force ◽  
Element Analysis ◽  
Angular Extrusion ◽  
Ultra High Molecular Weight

Abstract Ultra-high molecular weight polyethylene (UHMWPE) used in biomedical applications, e.g. as a bearing surface in total joint arthroplasty, has to possess superior tribological properties, high mechanical strength, and toughness. Recently, equal channel angular extrusion (ECAE) was proposed as a processing method to introduce large shear strains to achieve higher molecular entanglement and superior mechanical properties of this material. Finite element analysis (FEA) can be utilized to evaluate the influence of important manufacturing parameters such as the extrusion rate, temperature, geometry of the die, back pressure, and friction effects. In this paper we present efficient FEA models of ECAE for UHMWPE. Our studies demonstrate that the choice of the constitutive model is extremely important for the accuracy of numerical modeling predictions. Three considered material models (J2-plasticity, Bergstrom-Boyce, and the Three Network Model) predict different extrusion loads, deformed shapes and accumulated shear strain distributions. The work has also shown that the friction coefficient significantly influences the punch force and that the 2D plane strain assumption can become inaccurate in the presence of friction between the billet and the extrusion channel. Additionally, a sharp corner in the die can lead to the formation of the so-called “dead zone” due to a portion of the material lodging into the corner and separating from the billet. Our study shows that the presence of this material in the corner substantially affects the extrusion force and the resulting distribution of accumulated shear strain within the billet

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