Polyethylene Core Research Articles

Experimental studies of absorption properties of polymer composites based on core–shell fillers with hybrid shells

Microwave absorbing properties of polymer composites based on core-shell fillers with ultra-high molecular weight polyethylene core and GNP-carbonyl iron, GNP-cobalt oxide Co3O4, GNP-micro-sized MoS2, and GNP-barium hexaferrite BaFe12O19 hybrid shells were investigated in the frequency range of 40–60 GHz. Scanning electron microscopy sizing of the constituent particles in the composites showed the characteristic dimension of micron for Fe particles while Co3O4 and BaFe12O19 particles are found to be much smaller (nanometer-sized); MoS2 particles mostly form agglomerates and have diverse shapes and varying from 70 nm to 3–4 μm sizes. The shielding properties of composite materials (CMs) with 30 wt % Fe (Co3O4,MoS2, BaFe12O19) + C wt. % GNP/PEwith the GNP concentration c in the range of 1–5 wt% of nanocarbon are weakly frequency dependent. But the analyzed composites interaction with the electromagnetic radiation reveals significant influence of both the nanocarbon content and the additional dielectric or magnetic component type in the shell materials on the shielding parameters. The calculated values of the effective absorption coefficients Aeff for the investigated composites with different hybrid shells have shown that at 3 wt % GNP in the composite with 30 % Co3O4Aeff increases greatly and reaches 0.75, exceeding the correspondent values for the 30%BaFe12O19+GNP system. The primary contribution of absorption to the shielding characteristics of the investigated polymer CMs based on core-shell fillers with hybrid shells constitutes good prospects of applications.

Experimental characterization of aluminum/polymer/aluminum sandwich structures under various loading rates and temperatures: Establishing a constitutive relationship for LDPE

Composite sandwich structures, for example Alucobond, have appeared as auspicious materials in a diversity of engineering applications due to their lightweight, high strength to weight ratio and thermal insulation properties. Analyzing their mechanical behavior in different loading rates is critical to optimizing their performance. This study inspects the mechanical response of Alucobond sandwich composite structures under dynamic and quasi-static compression loadings. Dynamic compression tests, carried out at high strain rates, and quasi-static compression tests, carried out at lower strain rates and temperatures, were used to predict the behavior of the material under different loading conditions. In addition, the mechanical properties of the low-density polyethylene (LDPE) core layer were characterized under dynamic and quasi-static loading conditions, with varying strain rates and temperatures, leading to the establishment of a constitutive relationship for the LDPE material. The comparative study of Alucobond and LDPE highlights the influence of material composition and loading conditions on the mechanical behavior of the composite sandwich structures.

An in situ strategy to produce high-performance composite thermal adhesives with excellent bonding, thermal transfer and adjustable electrical performance based on a designer hyperbranched epoxy copolymer

Thermally conductive adhesives (TCAs) have attracted considerable attentions in recent years as they can simultaneously promote interfacial bonding and thermal transfer. So far, a lot of strategies have been explored for producing them. Among them, modifying adhesive resins with thermally conductive nanofillers is one of the most frequently reported methodologies, which often involves complicated process and tedious procedures. We herein report a facile strategy for producing TCAs via an in situ process with the assistance of a designer hyperbranched epoxy copolymer, HBPE@PGMA. This copolymer consists of a hyperbranched polyethylene (HBPE) core and multiple poly (glycidyl methacrylate) (PGMA) side chains, which can be synthesized under mild conditions by a two-step polymerization process. As a stabilizer, this copolymer is found to effectively promote the exfoliation of hexagonal boron nitride (h-BN), natural graphite or multi-walled carbon nanotubes (MWCNTs) in chloroform under sonication, rendering boron nitride nanosheets (BNNS), graphene and individually dispersed MWCNT, respectively. Meanwhile, some of the copolymer can be irreversibly adsorbed on the resultant nanofiller surface based on the noncovalent CH-π interactions. This makes them well dispersible in chloroform and allows us to obtain high-performance TCAs from their dispersions via in situ process directly using the copolymer as matrix. The resultant TCAs simultaneously exhibit excellent interfacial bonding, thermal transfer and adjustable electrical performance. This strategy paves a way for producing high-performance TCAs through in situ process with relatively simple process.

Bimodal coaxial fiber sensor for simultaneous strain and temperature sensing for composite manufacturing process

Coaxial structured fibers have gained significant attention in sensor applications due to their design flexibility and ability for multifunctionality. However, the complex and thicker structure of a sensor can lead to stress concentration and signal interference when utilized for strain monitoring in composite manufacturing processes. To address this issue, we propose a bimodal coaxial fiber sensor capable of simultaneous temperature and strain measurement during composite cure and strain monitoring, while preserving the mechanical properties of the fabricated composites. To achieve bimodal sensing, we employ a multi-shell structure consisting of a multi-conductive layer with varying concentrations of multiwalled carbon nanotubes and a PEDOT:PSS layer, applied to a creep-enhanced ultra-high molecular weight polyethylene core fiber using a simple dip-coating method. The bimodal coaxial fiber sensor exhibits a high gauge factor (>4.1), stable cyclic tensile response (>1000 cycles), and linear response to stepwise temperature cycles. Moreover, the sensor demonstrates high sensing accuracy (<3% error) in cure strain monitoring and maintains the fracture toughness of the composite (<1% discrepancy) wherein it is embedded. These results confirm the significant potential of the bimodal coaxial fiber sensor for various applications in the composite industry and other fields.

Synthesis and Thermoreversible Gelation of Coil-Rod Copolymers with a Dendritic Polyethylene Core and Multiple Helical Poly(γ-benzyl-L-glutamate) Arms.

Coil-rod copolymers with a dendritic polyethylene (DPE) core and multiple helical poly(γ-benzyl-L-glutamate) (PBLG) arms (DPE-(PBLG)n) were prepared by palladium-catalyzed copolymerization in tandem with ring-opening polymerization (ROP). Macroinitiator (DPE-(NH2)11) was firstly prepared by the group transformation of DPE-(OH)11 generated from palladium-catalyzed copolymerization of ethylene and acrylate comonomer. Coil-helical DPE-(PBLG)11 copolymers were prepared by ROP of γ-benzyl-L-glutamate-N-carboxyanhydride (BLG-NCA). These DPE-(PBLG)11 copolymers could form thermoreversible gels in toluene solvent, and the dendritic topology of the DPE core increased the critical gelation concentrations. The self-assembled nanostructure of gels was fully characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), and wide-angle X-ray diffraction (WAXD), and the morphology of the fibrous structure was a twisted flat ribbon through a self-assembled nanoribbon mechanism. The self-assembled fibers formed by DPE-(PBLG45)11 are more heterogeneous and ramified than previously observed fibers formed by PBLG homopolymer and block copolymers.

Ultrasonically welded eco-friendly sandwich panels based on upcycled thermoplastic core: An eco-mechanical characterisation

A structure's sustainability depends not only on its components, but also on the manufacturing process. The adhesive layer mostly increases the structural weight, reducing weight-specific properties, beside hindering its disassembly and sorting at end-of-life. This study investigates an alternative joining method based on ultrasonic welding for upcycled honeycomb core sandwich panels. Thermoplastic composite skins, reinforced with flax or glass fibres, are connected to an upcycled polyethylene core made from disposed bottle caps and tested under quasi-static and dynamic loads. A life cycle assessment evaluates the environmental benefits of skin/core welding compared with adhesive bonding. Welded panels made from similar skins and cores presented similar to higher weight-specific flexural properties of adhesive-bonded structures (up to 45 % increase), while specific energy absorption under impact is increased by up to 23 % with welded joints. Skin/core welding reduces the panel environmental damage by up to 71 %, with an increment of up to 130 % in its eco-mechanical efficiency.

Influence of Aspect Ratio on the Flexural and Buckling Behavior of an Aluminium Sandwich Composite: A Numerical and Experimental Approach.

In the field of engineering materials, lightweight and ultra-lightweight composites are used in real time to a greater extent, with high-performance targeting for tailor-made systems in aerospace, automotive, and biomedical applications. Sandwich composites are among the most popular lightweight materials used in structural and vehicle-building applications. In the present investigation, one such sandwich composite laminate composed of aluminum face sheets and a high-density polyethylene core was considered to analyze sandwich composites' flexural and buckling behavior experimentally and numerically. The influence of aspect ratios, such as length to thickness and width to thickness, on the flexural and buckling performance of sandwich composite laminates was explored in the study. Laminates with different widths, namely, 10, 12, and 15 mm, and a uniform thickness and length of 3 mm and 150 mm, respectively, were used for flexural analysis, whereas laminates with widths of 10, 12, and 15 mm and a uniform thickness and length of 3 mm and 350 mm, respectively, were used for buckling analysis. The geometrical influence of the laminates on mechanical performance was studied through performance measures such as critical bending load, flexural stiffness, inter-laminar shear stress, and critical buckling load. A significant influence of aspect ratio on the mechanical behavior of the laminates was observed using both experimental and numerical approaches. Flexural behavior was observed to be better at greater widths, namely, 15 mm, and with a minimum support span of 90 mm due to reduced spring back effects and increased bending resistance. A maximum width of 15 mm allowed for a higher buckling load capacity similar to that of bending resistance. A critical buckling load of 655.8 N seemed to be the maximum and was obtained for the highest aspect ratio, b/t = 5. The soft core and ductile metal face sheets offered combined resistance to both bending and buckling. A lower aspect ratio (span to thickness) rendered these sandwich laminates better in terms of both bending and buckling.

Optimization of Micro-Drilling of Laminated Aluminum Composite Panel (Al-PE) Using Taguchi Orthogonal Array Design.

Aluminum Matrix Composite (AMC) represents an innovative class of materials that is extensively utilized in industries such as automotive, defense, aerospace, structural engineering, sports, and electronics. This study investigates the thrust force, exit burr formation, changes in the micro-tool, and drilled hole diameters during the micro-drilling of an aluminum-polyethylene composite panel (Al-PE). The panel consists of 3501 series aluminum skin materials bonded to a polyethylene (PE) core. Micro-drilling test parameters were designed using Taguchi's L16 (42 23) orthogonal array. Tests were conducted with five control parameters: cutting speed with four levels (10 m/min, 20 m/min, 30 m/min, 40 m/min), feed rate with four levels (0.5 µm/rev, 1 µm/rev, 2 µm/rev, 4 µm/rev), the tool diameter with two levels (0.7 mm, 1 mm), and tool point angle with two levels (100°, 140°) using both AlTiN-coated and uncoated drills. The maximum thrust force (Fz), maximum burr height, and changes in both the drill tool and hole diameters were measured for analysis of variance (ANOVA). The results showed that, in terms of impact on Fz, tool point angle had the highest positive influence (64.54%) on the micro-drill at the entrance of composite (upper aluminum plate). The cutting speed had the highest positive influence (45.32%) on the tool in the core layer (PE core layer). The tool point angle also had the highest positive influence (68.95%) on the micro-drill at the lower layer of the composite (the lower aluminum plate). There was noticeable chip adhesion on the major cutting edge and nose area under micro-drilling conditions with higher thrust forces and burr height. The AlTiN coating had a positive effect on tool wear and hole diameter deviations, but it adversely affected the burr height.

Finite element analysis of optimized novel additively manufactured non-articulating prostheses for cervical total disc replacement.

Ball-and-socket designs of cervical total disc replacement (TDR) have been popular in recent years despite the disadvantages of polyethylene wear, heterotrophic ossification, increased facet contact force, and implant subsidence. In this study, a non-articulating, additively manufactured hybrid TDR with an ultra-high molecular weight polyethylene core and polycarbonate urethane (PCU) fiber jacket, was designed to mimic the motion of normal discs. A finite element (FE) study was conducted to optimize the lattice structure and assess the biomechanical performance of this new generation TDR with an intact disc and a commercial ball-and-socket Baguera®C TDR (Spineart SA, Geneva, Switzerland) on an intact C5-6 cervical spinal model. The lattice structure of the PCU fiber was constructed using the Tesseract or the Cross structures from the IntraLattice model in the Rhino software (McNeel North America, Seattle, WA) to create the hybrid I and hybrid II groups, respectively. The circumferential area of the PCU fiber was divided into three regions (anterior, lateral and posterior), and the cellular structures were adjusted. Optimal cellular distributions and structures were A2L5P2 in the hybrid I and A2L7P3 in the hybrid II groups. All but one of the maximum von Mises stresses were within the yield strength of the PCU material. The range of motions, facet joint stress, C6 vertebral superior endplate stress and path of instantaneous center of rotation of the hybrid I and II groups were closer to those of the intact group than those of the Baguera®C group under 100N follower load and pure moment of 1.5 Nm in four different planar motions. Restoration of normal cervical spinal kinematics and prevention of implant subsidence could be observed from the FE analysis results. Superior stress distribution in the PCU fiber and core in the hybrid II group revealed that the Cross lattice structure of a PCU fiber jacket could be a choice for a next-generation TDR. This promising outcome suggests the feasibility of implanting an additively manufactured multi-material artificial disc that allows for better physiological motion than the current ball-and-socket design.

The effect of cyanoacrylate on knot elongation in three sutures used for prosthetic laryngoplasty in the horse.

This study investigated the elongation following cyclic loading on square knots of 5 USP multifilament long-chain ultra-high molecular weight polyethylene core (UHMWPE), 2 mm woven UHMWPE tape, and 5 USP braided polyester, with and without cyanoacrylate glue. Experimental study. n=4. Three conditions (suture without knot, suture with knot, suture with knot + cyanoacrylate) were evaluated for each suture material on a mechanical test stand by measuring the increased length of the construct after cycling from 25 to 50N for 1000 repetitions at 20 mm/second. Knot elongation was determined by subtracting the length of the control suture from the suture with knot or suture with knot + cyanoacrylate. The data were analyzed with a linear regression model with robust estimation of variance. Post-hoc analysis determined the model adjusted differences (square knot vs. cyanoacrylate) as a difference from control. t-tests were conducted to identify the significant findings. Total elongation of polyester (6.2-7.8 mm) was greater than multifilament UHMWPE (3.4-6.4 mm) and UHMWPE tape (2-3.7 mm) for all conditions. Polyester had the lowest knot elongation (1.6 mm) and the addition of cyanoacrylate decreased knot elongation for polyester by 1 mm. Polyester had the most total construct elongation followed by multifilament UHMWPE and UHMWPE tape. Polyester showed the least knot elongation and cyanoacrylate decreased this knot elongation. Total construct and knot elongation should be considered as contributing factors to loss of arytenoid abduction following prosthetic laryngoplasty when using polyester, multifilament UHMWPE, or UHMWPE tape. Addition of cyanoacrylate to polyester knots should be explored to limit elongation.

Effects of Microwave‐Assisted Cross‐Linking on the Creep Resistance and Sensing Accuracy of a Coaxial‐Structured Fiber Strain Sensor

AbstractNanocomposites have been widely studied for sensor applications because of their high design flexibility. However, the creep behavior of polymeric materials is a crucial issue of nanocomposite‐based strain sensors in terms of sensing accuracy in high‐temperature environments, which acts as a bottleneck for the use of nanocomposites in embedded type sensors for monitoring the curing reactions and structural health of composite. Herein, we suggest a microwave‐assisted cross‐linking method for enhancing the reliability of polymer‐based coaxial‐structured fiber strain sensors in high temperatures. A dry‐jet wet‐spun ultra‐high molecular weight polyethylene core fiber with a microwave post‐treatment in a peroxide bath provided superior strength (2.1 GPa), modulus (69 GPa), and enhanced creep resistance (&gt;94%). By using a creep resistance‐enhanced core fiber, coaxial‐structured fiber strain sensors, which have multi‐layer structured shell parts, could be fabricated via the simple dip‐coating method. The fabricated coaxial‐structured fiber strain sensor showed a high gauge factor (4.12 with strain range of 0%–1%), a low‐temperature sensitivity coefficient (−6.5 × 10−4), and an improved sensing accuracy (&lt;3% error at 80 °C) in high‐temperature environments. From these results, it can be confirmed that the microwave‐assisted cross‐linking method is very promising for use in nanocomposite‐based strain sensors for various application fields.

Upcycling opportunities and potential markets for aluminium composite panels with polyethylene core (ACP-PE) cladding materials in Australia: A review

Many buildings worldwide have high fire-risk materials as part of their cladding. As governments in Australia strive to make buildings safer, it is expected that a large volume of end-of-life dangerous cladding will be replaced with safer materials. This high volume of hazardous materials might be upcycled into value-added products. This article presents a systematic market analysis and literature review in identifying current and potential uses for the raw materials used in hazardous ACP-PE cladding. The most promising areas were identified to be non-food-contact packaging (US$228 M p.a.), non-pressure pipes (US$30 M p.a.), footwear (US$5.29 M p.a.) and 3D printer filament (US$2.73 M p.a.)

In situ formation of core‐shell rubber particles in polypropylene matrix by melt blending and its effects on the toughness and stiffness of the composites

AbstractToughening of thermoplastics with a one‐phase impact modifier generally results in significant reduction in stiffness, whereas core‐shell rubber modifiers have extra structural parameters such as core rigidity and shell flexibility, by controlling which the stiffness and impact toughness of their composites can be better balanced. In this study, three kinds of polyethylene (PE) with different rigidity are used respectively to prepare polypropylene/ethylene–propylene rubber/polyethylene (PP/EPR/PE) ternary composites by melt blending, in which the EPR‐to‐PE ratio is 1:1. Atomic force microscopy‐infrared (AFM−IR) and scanning electron microscopy (SEM) results indicate that core‐shell rubber particles with a PE core and an EPR shell are formed in situ and uniformly dispersed in the PP matrix. Mechanical measurements show that at the same modifier content the PP composites toughened with these core‐shell rubber particles exhibit higher toughness and stiffness than that with EPR alone, and the more rigid the PE core, the greater the effects. These results are in quantitative agreement with a recent theoretical model, providing solid experimental evidence in support of the latter. Furthermore, this work demonstrates an economical approach to toughening PP by partial substitution of the EPR with the much cheaper PE for better performance.

Experimental study of the core role of GFRP and LDPE on the collapse behavior of absorbers printed with PLA and ABS

Since the advent of polymeric materials, many structures have always been built for engineering purposes. On the one hand, the emergence of composites containing glass fibers has had a significant impact on reducing the weight of structures in various industries. On the other hand, with the advent of 3D printers, many limitations for the geometry of engineering structures were removed. In this research, due to the wide application of these two sciences, a new type of composite absorbers has been introduced. The presented absorbers have glass fiber-reinforced polymer cores (GFRP) or low-density polyethylene cores (LDPE), the shells of each sample are made of PLA or ABS. In this study, 24 different samples were tested under quasi-static loading. The samples were examined in three different groups. In the first group, no cores were used, but in the second group, GFRP cores were used, and in the third group, LDPE cores were used. Triangular, trapezoidal, semielliptical, and square sections were studied, and the results showed that the lowest maximum force was related to samples with semielliptical cross section, then the maximum force increased by changing the cross section from triangular to trapezoidal and then to a square. In addition, the maximum force was higher in the GFRP core than in the LPDE core.

The influence of the viscoelastic property of polycarbonate urethane as an artificial disc core material under various physiological motions at the L4-L5 level.

Intervertebral disc (IVD) degeneration is one of the musculoskeletal disorders due to the Degenerative Disc Disease (DDD), that cause low back pain (LBP) and leads to a reduced range of motion. Spinal fusion and arthroplasty are the other surgical procedures that could replace the disc affected by DDD against artificial disc replacement (ADR). This study aims to analyse the biomechanical behaviour of proposed core material as Polycarbonate Urethane (PCU) in the L4-L5 lumbar segment for ADR with Ti-6Al-4V and Co-28Cr-6M as endplate materials and compare it to the performance of an ultra-high molecular weight polyethylene (UHMWPE) core. Finite element methods have been approached to measure the overall stress distribution along with other physiological motions like Flexion (FLEX), Extension (EXT), Axial rotation (AR) and Lateral bending (LB), respectively. Preload of 450 N compressive load, 8 N-m for Flex, 6 N-m for EXT, 6 N-m for AR and 4 N-m for LB are applied. It could be concluded that Ti-6Al-4V - PCU and Co-28Cr-6M - PCU is the best composition for the ADR for the L4-L5 level.

Elastic interface in few‐layer graphene/poly(vinylidenefluoride‐trifluoroethylene‐chlorofluoroethylene) nanocomposite with improved polarization

AbstractPolymer film capacitor exhibits extensive applications in advanced electronics because of its flexibility and huge power density. The current research interests of polymer capacitor are addressed on large energy density and high charge–discharge efficiency of composite film. Here we developed the compatible elastic interface composed of hyperbranched poly(methyl acrylate) copolymer in graphene/poly(vinylidenefluoride‐trifluoroethylene‐chlorofluoroethylene) (P(VDF‐TrFE‐CFE)) nanocomposite with high energy capability. This hyperbranched copolymer comprising polyethylene core that was grafted with poly(methyl acrylate) (PMA) segments and pyrene units was synthesized by atom transfer radical polymerization. The few‐layer graphene was exfoliated with assistance of hyperbranched copolymer that was attached on surface of flakes via π‐π non‐covalent interactions between pyrene groups and delocalized π electrons of nanosheets. Graphene/P(VDF‐TrFE‐CFE) nanocomposite film was prepared by solution casting method. The compatibility between graphene and fluoropolymer is greatly improved due to the elastic interphase of PMA segments in hyperbranched copolymer, which enhances the interfacial polarization and decreases the accumulation of charge carriers under high electric field. The energy density of 7.0 J/cm3 with charge–discharge efficiency of 60% at 300 MV/m is achieved for 0.1 wt% nanocomposite. This work reveals an effective architecture of polymer composite with elastic interface to increase the energy capability of polymer dielectric film.

Engineering design of sustainable aluminium composite material with rice husk core

ABSTRACT In the current scenario, colossal demand for state-of-the-art green composites has surged significantly to be exploited in commercial applications with a concurrent need to curtail plastics. The present study targets Aluminium Composite Materials (ACM) with a polyethylene core that can be substituted by rice husk (RH), a hard protective sheath of rice grains. Rice husk is a paragon of eco-friendliness and a productive latent agricultural byproduct. The current investigation focuses on designing and fabricating an ACM with rice husk core in different proportions of rice husk (5, 10, 15, and 20% by weight) with epoxy resin to form a laminate and sandwiched between aluminium sheets. Its various physical, mechanical, and environmental properties were examined to correlate with commercially existing ACMs, composites made from agricultural residues, plywood, and hardboards. It was observed that the proposed composite is light-weight with low water absorption, appreciable tensile and flexural strength, and vibration modes beyond the frequency range of operation. It is envisaged that the eco-friendly ACM with the rice husk core would be a promising eco-solution for daily-use applications like signage, hoarding, and frames.

FURAÇÃO DE MATERIAL SANDUÍCHE EMPREGANDO BROCAS COM GEOMETRIAS DIFERENTES: CONSTRUÇÃO DE MODELO MATEMÁTICO PARA PREVISÃO DA FORÇA DE AVANÇO

Os materiais sanduíche são assim denominados pois combinam as propriedades de dois diferentes materiais, adquirindo uma estrutura com um núcleo e duas faces externas. Uma das formas de processar este material é por meio da usinagem, mais especificamente em operações de furação, que foi o foco dessa pesquisa. A redução dos esforços de corte é desejada durante a operação de furação, impactando melhor qualidade dos furos devido a redução das vibrações no sistema. Também pode aumentar a vida útil das ferramentas, eliminando custos devido ao maior tempo para substituição das mesmas. Partindo deste princípio, esta pesquisa aliou conhecimentos estatísticos aplicados à engenharia, a fim de construir modelos matemáticos para prever o comportamento da força de avanço na furação de material sanduíche empregando brocas com geometrias diferentes, denominadas Brad &amp; Spur, helicoidal com duas arestas e helicoidal com três arestas e. O objetivo foi elaborar equações de regressão linear múltiplas para identificar a influência da velocidade de corte e do avanço sobre a força de avanço para cada uma das brocas estudadas. Além disso, foi investigado se a geometria das brocas impactou em um comportamento que pudesse ser modelado por meio de equações matemáticas, com um determinado grau de confiança aceitável.

Review of techniques for identifying the chemical composition of Aluminium Composite Cladding cores

The Grenfell disaster of June 14, 2017 brought into sharp focus the dangers posed by combustible façade materials. Polyethylene core panelling has been implicated in numerous fires such as The Address Downtown, the Saif Belhasa in Dubai and the Lacrosse building in Melbourne. Due to the large number of buildings with potentially combustible cladding, there is significant pressure to find an accurate and fast method to identify such cladding and any associated insulation as part of the overall assessment process. Over the past year, several different approaches to identification have been proposed and in this paper, we recount our expe-riences in developing a methodology to achieve this and discuss the limitations of this method and of competing methods.

Development of a Biconcave Mobile‐Bearing Lumbar Total Disc Arthroplasty Concept Using Finite Element Analysis and Design Optimization

Total disc arthroplasty (TDA) is a motion-preserving surgical treatment for spinal disorders. However, adverse surgical outcomes, such as abnormal kinematics, facet joint (FJ) overloading, and polyethylene (PE) failures, have limited wide application of lumbar TDAs. The objectives of this computational study were to elucidate how implant design and FJ articulation both influence metal-on-polyethylene (MoP) motion and contact mechanics, as well as to propose and refine a new mobile-bearing TDA concept which enhanced postoperative performance. Simulation results show that abnormal motions (lift-off and/or unsymmetrical motion) are alleviated in fixed-/mobile-bearing TDA-treated segments, as the FJ gap increases. It clearly demonstrates that FJ articulation guides segmental motion and interferes with intended MoP articulation. For an existing biconvex mobile-bearing design, component impingement leads to a peak PE stress of 20.8 MPa (yield stress: 13 MPa), indicating a high risk of PE creep/fracture. Therefore, we proposed a new TDA concept featuring a biconcave PE core with a smooth shape, in order to strengthen the PE rim and mitigate edge-loading. Furthermore, the biconcave-core TDA was optimally designed to promote normal segmental range of motion (ROM), or to minimize polyethylene contact pressure (PCP). In extension (the severest loading scenario), the biconvex-core TDA design caused a ROM 3.6° (+88%) greater than the intact segment and a peak PCP of 116.5 MPa. In contrast, ROM-optimal or PCP-optimal biconcave-core TDA designs decreased the ROM difference to 0.0° or the peak PCP to 24.3 MPa. Therefore, this new TDA design can potentially reduce the incidence of hypermotion and PE damage. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1805-1816, 2019.