Joint Material Research Articles

Effects of Diffusing Squalene on the Plastic Deformation of Ultrahigh-Molecular-Weight Polyethylene─Insights from Molecular Dynamics Simulations.

Ultrahigh-molecular-weight polyethylene (UHMWPE) stands out as a popular artificial joint material. However, wear limits its service life, which is mainly caused by accumulation of plastic deformation. The plastic deformation on the frictional interface reflects the early wear of UHMWPE. To investigate the effect of squalene, a typical component in the body fluid, on the tribological properties of UHMWPE at microscopic scale, the diffusion behavior of squalene into polyethylene and its influence on the plastic deformation of polyethylene are discussed using the molecular dynamics (MD) simulation. The lubrication model shows that polyethylene reconstructed from the interface to lower substrate, with refactor gaps between polyethylene chains. This promotes squalene molecules to gradually diffuse into polyethylene from these gaps and causes the polyethylene structure to become loose. On the other hand, in the diffused model, squalene in polyethylene substrates increases the plastic deformation of polyethylene. The separation of squalene reduces the interaction strength between adjacent polyethylene chains and accelerates the disentanglement of polyethylene. The flexibility of "C═C" bonds in squalene allows the continuous adjustment of its spatial structures to adapt the space between polyethylene chains. The squalene fragments will not hinder the plastic flow of polyethylene.

Life Cycle Cost Analysis and Deterioration Patterns of Limestone Paving

Stone is a durable and high-performance paving material in standard and in intensive service regimes. Stone is thus a preferable material for sidewalk and promenade paving under intensive service regimes, such as touristic promenades and historic sites. Recent studies on the weathering and degradation of stones in buildings have revealed differing analytical approaches among geologists, geo-engineers, and civil engineers. The present research aims to develop a structured analytical–empirical methodology for the assessment of stone pedestrian pavements’ life cycle and life cycle costs. This study presents an integrated methodology that combines diagnostic field surveys, core laboratory tests, and the characterization of deterioration patterns. This approach allows for evaluating how faulty construction methods impact the durability and degradation of natural stone pedestrian pavements. It also assesses their effect on the pavement’s life cycle and associated costs. The diagnostic field survey concentrates on specific construction details, including: (a) Cracks in the paving stones. (b) Peeling of stone layers. (c) Subsidence and cracking at the paving edges. (d) Cracking of filler materials in joints between stone slabs. The laboratory tests focus on five core physical properties for the stone deterioration: (1) apparent density, (2) Water absorption, (3) Compressive strength, (4) Flexural strength, and (5) Abrasion resistance. This study proposes linear and exponential patterns for deterioration. A case study carried out on a Capernaum promenade revealed excessive deterioration patterns caused by the poor core properties of the paving stone and defective construction. The consequences of excessive deterioration on life cycle costs result in additional expenses of 73%, indicating a reduction in the life cycle. The novelty of this research lies in developing and delivering an integrated methodology that enables the assessment of how defective construction methods impact the durability, deterioration, life cycle, and life cycle costs of natural stone pedestrian pavements.

Strength, Durability, and Aesthetics of Corner Joints and Edge Banding in Furniture Design: A Review

Corner joints and edge banding are essential components that significantly impact the strength, durability, and aesthetic appeal of particleboard furniture. This review examines the critical role of edge banding in enhancing the performance of corner joints, which are fundamental to the overall quality of panel furniture. A targeted literature search was conducted across key databases, including the Web of Science Core Collection (WoS CC), Scopus, and Google Scholar, focusing on scientific resources in the technical and biotechnical sciences. The selection of joint types, materials, and construction methods can substantially influence both the structural integrity and visual design of the furniture. Well-designed corner joints improve durability and longevity by ensuring that furniture can withstand various forces and loads without failure or deformation. These joints enhance the aesthetics of furniture by providing seamless and visually appealing connections between different elements. Edge banding is vital for reinforcing corner joint strength, as different materials exhibit varying degrees of resistance to impact, scratches, and abrasion, thereby safeguarding furniture surfaces. Also, edge banding contributes to the furniture’s longevity, ensuring durability during use as well as through disassembly and transport during remodeling or relocation. This review aims to consolidate existing knowledge and establish parameters for future research on the quality and performance of corner joints and edge bands in particleboard furniture.

Strong Bonding of Robust Lubricating Hydrogels to Porous Substrates for Joint Replacement.

Hydrogels with excellent mechanical and lubrication properties have been developed rapidly, laying the foundation for their application in cartilage replacement. However, the combination of robust hydrogels and substrates under different forms of movement is a great challenge. In addition, due to differences in modulus, the stress shielding effect caused by implantable artificial joint metal materials can lead to bone resorption. Here, we proposed to combine a 3D printed porous titanium alloy with a high-strength lubricating hydrogel to construct an integrated joint substitute material. The porous titanium alloy TC4 substrate constructed by 3D printing possesses a modulus similar to that of human bone. The strong bonding of the hydrogel and TC4 was achieved through two strategies: mechanical interlocking and chemical bonding. The combination of the alloy substrate and hydrogel realizes the construction of a bionic lubricating cartilage layer on the surface of traditional artificial joint materials. The hydrogel has excellent bonding properties with the porous substrate under different test conditions. Truly human-like joint sockets were prepared for the first time with soft-soft and soft-hard contact modes. Under conditions simulating human motion, the hydrogel maintains a low friction coefficient and still has excellent substrate adhesion after 100,000 cycles. This study further pushes the application of hydrogels in biolubrication into practice.

Exploring alternative polymer materials for joint liners: a software-guided material selection

This study explores the alternative polymer materials and selection process for joint implant liners, focusing on applying CES Selector software to identify suitable polymer materials. CES Selector provides an easy-to-use interface. It offers multiple selection methods, including boundary values and property constraints. Seven materials were excluded from the analysis, resulting in 19 potential candidates, including unconventional options like EVOH, PCTA, PESU, PI, PPA, PPC, PPSU, and PSU. The materials underwent evaluation based on key criteria, including tensile strength, Young’s modulus, compressive strength, fatigue strength, and fracture toughness. Overall, TPU exhibited a remarkable combination of high mechanical strength and adaptable Young’s modulus, making it a top contender. However, in other evaluation criteria, PI surpassed TPU, solidifying its potential as a superior choice. This systematic approach provides valuable insights for engineers and designers seeking innovative materials for joint implant liners. The study results broaden the range of materials used in implant manufacturing, providing potential alternatives that offer better long-term durability and performance.

Research on the Corrosion Resistance and Cytotoxicity of Medical Forged Co-28Cr-6Mo Alloy

Co-Cr-Mo alloy as a human body implant material has a long history, because of its excellent corrosion resistance and biocompatibility, and is widely used in human hip joint materials. Co-Cr-Mo alloy in the human body is often in a passivation state; the formation of dense oxide film on the alloy surface prevents further corrosion of the alloy. The main component of the passivation film is the oxide of Cr, so a layer of oxide film formed by Cr on the surface of Co-Cr-Mo alloy is the reason for its good corrosion resistance. In biocompatibility, cytotoxicity is the first choice and necessary option for biological evaluation, and cytotoxicity can quickly detect the effect of materials on cells in a relatively short time. Therefore, this research conducted a comparative evaluation on the corrosion resistance and biocompatibility of forged Co-Cr-Mo alloys produced in domestic and foreign alloys in line with medical standards. Three simulated human body fluids and Princeton electrochemical station were selected for corrosion resistance experiments, and it was found that the corrosion resistance of four alloys in sodium citrate solution inside and outside China would be reduced. All the alloys exhibit secondary passivation behavior in Hanks solution, which improves the corrosion resistance of the alloys. According to the self-corrosion potential Ecorr analysis, the corrosion resistance of domestic B alloy is the best, while that of foreign R31537 alloy is poor. In the biocompatibility experiment, the biocompatibility of Co-Cr-Mo alloy was evaluated through the measurement of contact Angle and cytotoxicity reaction. The experimental results show that Co-Cr-Mo alloy is a hydrophilic material, and the contact Angle of foreign R31537 alloy is smaller, indicating that the surface of R31537 alloy is more suitable for cell adhesion and spreading. According to the qualitative and quantitative analysis of the cytotoxicity experiment, the toxic reaction grade of domestic A, B and R31537 alloy is grade 1, the toxic reaction grade of C alloy is grade 2, and C alloy has a slight toxic reaction.

Shear mechanical properties and fracturing responses of layered rough jointed rock-like materials

Shear mechanical properties and fracturing responses of layered rough jointed rock-like materials

Optimization of Shear Resistance in Horizontal Joints of Prefabricated Shear Walls through Post-Cast Epoxy Resin Concrete Applications

The horizontal joint is a critical component of the prefabricated shear wall structure, responsible for supporting both horizontal shear forces and vertical loads along with the wall, thereby influencing the overall structural performance. This study employs direct shear testing and finite element analysis to investigate the horizontal joint in walls with ring reinforcement. It examines the impact of various factors on joint shear performance, including the type of joint material, joint configuration, buckling length of ring reinforcement, strength of precast concrete, reinforcement ratio of ring reinforcement and dowel bars, and the effect of horizontal binding force. The findings indicate that the shear bearing capacity and stiffness of joints incorporating post-cast epoxy resin concrete and keyways are comparable or superior to those of integrally cast specimens. A larger buckling length in ring reinforcement may reduce shear strength, suggesting an optimal buckling length at approximately one-third of the joint width. As the strength of precast concrete increases, ductility decreases while bearing capacity increases, initially at an increasing rate that subsequently declines. Optimal results are achieved when the strength of precast concrete closely matches that of the post-cast epoxy concrete. Enhancing the reinforcement ratio of ring reinforcement improves shear capacity, but excessively high ratios significantly reduce ductility. It is recommended that the diameter of ring reinforcement be maintained between 10 mm and 12 mm, with a reinforcement ratio between 0.79% and 1.13%. Increasing horizontal restraint enhances stiffness and shear capacity but reduces ductility; thus, the axial compression ratio should not exceed 0.5.

RESEARCH ON THE DESTRUCTION PROCESSES OF WELDED JOINTS UNDER CONDITIONS OF DETACHMENT OF THE VERTICAL STEEL TANK BODY FROM THE BOTTOM DURING A FIRE

The study presents a comprehensive analysis of welded joints by applying advanced mathematical modelling and experimental research methods. The primary objective was to develop and validate a methodology for mathematical modelling of the behaviour of welded joints under mechanical loading, as well as to assess the effectiveness of the proposed approaches in predicting their strength and durability. Based on the research results, we can draw the following conclusions. The authors obtained the results of welded joint samples and analysed the corresponding curves of the dependence of force factors on their deformations. The study showed that the destruction of welded joints occurs mainly along the weld seam, where the strength is lower than in the base material of the rods. It is consistent with the practical data of the experiment, which confirms that the weld is the weakest link in the structure. The article substantiated a set of provisions and assumptions for implementing mathematical modelling of the behaviour of samples of welded joints imitating welded joints in a reservoir for petroleum products under mechanical tensile tests. The test results justified the mathematical models of the steel material of welded joints of petroleum product tanks and obtained numerical parameters of the mechanical properties of steel of welded joints. Yield strength is in the range of 240–300 MPa, the modulus of elasticity is 190–240 GPa, the hardening modulus is 18–20 GPa, and the ultimate plastic deformation is 0.00334. Based on a complex of well-founded mathematical models of welded joints, we carried out calculations regarding the numerical study of the behaviour of welded joints under the conditions of their mechanical tests. We compared the obtained results with the results of experimental tests and, based on this comparative analysis, established that they were adequate since the Fisher criterion did not exceed the tabular value and the relative error did not surpass 12%. The findings of this research offer valuable insights and practical recommendations for improving the design and evaluation of welded structures, enhancing their performance and safety in engineering applications.

Dynamic behaviors of general composite beams using mixed finite elements

A novel mixed finite element method is developed and implemented for analyzing the vibration and buckling behavior of general composite beams which consists both transversely layered and axially jointed materials. The governing state-space equations are derived using the Hamilton's principle, where both displacements and stresses are treated as fundamental variables. This semi-analytical method uses transfer relations in the transverse direction and finite element meshing in the longitudinal direction, overcoming the difficulties for general composite beams analysis and providing computational efficiency and analyzing flexibilities. The developed mixed finite element model ensures continuity of both displacements and stresses across the material interface, thereby resolving interfacial stress singularity issues and offering more reliable simulations of boundary conditions at both ends. The proposed method is formulated and validated for the free vibration and buckling analysis of general composite beams. Additionally, it is observed that material properties such as Young's modulus and density, as well as the stiffness of the interface connecting layers, have significant effects on the free vibration and buckling responses of the composite beams. Analysis of periodically distributed and bi-directional composite beams demonstrates the versatility of this method in handling two types of combination forms. The proposed method serves as a valuable reference for obtaining accurate vibration and buckling results while ensuring stress-compatibility for composite beams in practical applications.

Improving the lubricity of titanium alloy joint by using tough, antibacterial and strongly adhesive hydrogel

Titanium alloy, especially Ti6Al4V, has gained widespread recognition as a material for joint implant. Aiming at the problems such as high friction and easy infection of Ti6Al4V implant materials in practical applications, a strategy of surface modification of Ti6Al4V was proposed. Inspired by the articular cartilage, a tough hydrogel integrated with lubricating and antibacterial properties was prepared in this work, and tightly applied to the Ti6Al4V surface with an adhesive agent. The strength of the hydrogel coating was similar to that of human articular cartilage, and play remarkable lubricating and antibacterial effects at the same time. This work presented new perspectives on the application of hydrogel coatings in biomedicine, underwater equipment, smart manipulation, and other fields.

Reliability Risk Mitigation in Advanced Packages by Aging-Induced Precipitation of Bi in Water-Quenched Sn-Ag-Cu-Bi Solder.

Bi-doped Sn-Ag-Cu (SAC) microelectronic solder is gaining attention for its utility as a material for solder joints that connect substrates to printed circuit boards (PCB) in future advanced packages, as Bi-doped SAC is reported to have a lower melting temperature, higher strength, higher wettability on conducting pads, and lower intermetallic compound (IMC) formation at the solder-pad interface. As solder joints are subjected to aging during their service life, an investigation of aging-induced changes in the microstructure and mechanical properties of the solder alloy is needed before its wider acceptance in advanced packages. This study focuses on the effects of 1 to 3 wt.% Bi doping in an Sn-3.0Ag-0.5Cu (SAC305) solder alloy on aging-induced changes in hardness and creep resistance for samples prepared by high cooling rates (>5 °C/s). The specimens were aged at ambient and elevated temperatures for up to 90 days and subjected to quasistatic nanoindentation to determine hardness and nanoscale dynamic nanoindentation to determine creep behavior. The microstructural evolution was investigated with a scanning electron microscope in tandem with energy-dispersive spectroscopy to correlate with aging-induced property changes. The hardness and creep strength of the samples were found to increase as the Bi content increased. Moreover, the hardness and creep strength of the 0-1 wt.% Bi-doped SAC305 was significantly reduced with aging, while that of the 2-3 wt.% Bi-doped SAC305 increased with aging. The changes in these properties with aging were correlated to the interplay of multiple hardening and softening mechanisms. In particular, for 2-3 wt.% Bi, the enhanced performance was attributed to the potential formation of additional Ag3Sn IMCs with aging due to non-equilibrium solidification and the more uniform distribution of Bi precipitates. The observations that 2-3 wt.% Bi enhances the hardness and creep strength of the SAC305 alloy with isothermal aging to mitigate reliability risks is relevant for solder samples prepared using high cooling rates.

Adhesion-Lubrication Paradox of Articular Cartilage.

The friction of solids is primarily understood through the adhesive interactions between the surfaces. As a result, slick materials tend to be nonstick (e.g., Teflon), and sticky materials tend to produce high friction (e.g., tires and tape). Paradoxically, cartilage, the slippery bearing material of human joints, is also among the stickiest of known materials. This study aims to elucidate this apparent paradox. Cartilage is a biphasic material, and the most cited explanation is that both friction and adhesion increase as load transfers from the pressurized interstitial fluid to the solid matrix over time. In other words, cartilage is slippery and sticky under different times and conditions. This study challenges this explanation, demonstrating the strong adhesion of cartilage under high and low interstitial hydration conditions. Additionally, we find that cartilage clings to itself (a porous material) and Teflon (a nonstick material), as well as other surfaces. We conclude that the unusually strong interfacial tension produced by cartilage reflects suction (like a clingfish) rather than adhesion (like a gecko). This finding is surprising given its unusually large roughness, which typically allows for easy interfacial flow and defeats suction. The results provide compelling evidence that cartilage, like a clingfish, conforms to opposing surfaces and effectively seals submerged contacts. Further, we argue that interfacial sealing is itself a critical function, enabling cartilage to retain hydration, load support, and lubrication across long periods of inactivity.

Mechanical Properties of Carbon Fiber-Reinforced Plastic with Two Types of Bolted Connections at Low Temperatures.

Carbon fiber-reinforced plastic (CFRP) is frequently utilized as a bolted joint material in aircraft applications because of its high specific strength and specific modulus. Therefore, the performance of CFRP under -50° is significant. Here, we discuss the specimens of two bolted connections (single-nailed and double-nailed) used for static load tensile and tensile fatigue tests. We obtained the failure curves and fatigue life relationships of the specimens with two different connection methods at different tightening torques (2 N/m, 4 N/m, and 6 N/m) and low room temperatures. Our analysis reveals the effect of the bolt tightening torque and temperature on the structural mechanical properties of a CFRP bolted joint. It provides a data reference for researchers to design a composite bolted joint structure in an airplane flight environment.

Prediction of Residual Life of In-Service P91 Steel Joints Based on Fracture Behavior.

P91 steel and P91 steel joints experience performance degradation after serving for 30,000 h in working conditions. To clarify the damage and failure behavior and remaining life of the joints during subsequent service, further creep testing was conducted on the welded joints of P91 steel that had been in service for 30,000 h at three temperatures: 550 °C, 575 °C, and 600 °C. The fracture surface and the cross-section damage behavior were characterized by SEM and EBSD methods. The results show that there are two types of fracture modes in the joints at different temperatures: ductile cracking occurring at the BM, and type IV cracking occurring in the FGHAZ. The threshold stress for fracture mode transition decreases with an increase in working temperature. Type IV cracking near the HAZ is the main reason for the premature failure of joints during service. And based on the fracture mode, the dual-constant L-M method was proposed to predict the strength of in-service joint materials. The testing data are discussed and classified based on the fracture mode in this method, which has high accuracy and can prevent the premature failure of joints.

Converting “sliding” to “rolling” design for high-performance lubricating hydrogel

Despite the excellent lubricity of conventional hydrogel materials due to their wet-soft properties, they produce severe mechanical elastic deformation at higher interfacial contact stresses. Balancing the load-bearing capacity and lubricating properties of hydrogel material is the difficulty of the current research work for articular cartilage substitutes. Great progress has been made in developing bionic joint materials with high load-bearing and low-friction hydrogels based on gradient designs. However, most bionic materials are based on sliding friction greatly limiting the improvement of lubrication performance. Herein, we designed and prepared a new hydrogel material with high load-bearing capacity and stable lubrication performance, breaking through the traditional friction method and turning to “sliding” for “rolling”. The network on the hydrogel surface was dissociated by UV irradiation and the pores on the surface were filled with SiO2 nanoparticles. The dense network structure of the underlying layer endows the hydrogel material with good load-bearing properties, while the high degree of hydration of the surface layer and the rolling friction effect of SiO2 nanoparticles greatly enhance the lubrication property. With the synergistic effect of these designs, the multi-layered hydrogel with nanoparticles on the surface achieved an ultra-low average coefficient of friction (COF) of ∼0.00809 at a high load of 50 N during 30,000 cycles. This idea of hydrogel material design provides a new strategy for the replacement of biomimetic articular cartilage materials.

Microstructure and Mechanical Characteristics of Friction Welded Joint between Alumina and Aluminum Casting Alloy

In this study, the Al2O3 round bar and Al-Si12CuNi (AC8A) round bar were joined by friction welding. AC8A is a typical piston material treated by the heat treatment T6. The parameters of the joining condition are friction time and upset pressure. SEM observed the microstructure at the interface region of joined materials. 1) Judging from these photographs, the damages to the microstructures at the interface region of joined materials by upset pressure are more significant than those caused by friction time. 2) The relationship between the joint conditions and mechanical characteristics from three points of bending test results for the joint material specimens. 3) The residual stresses around the interface were measured by the Raman spectroscopy method. There is a possibility that the friction welding conditions are correlated to the residual stresses.

Finite Element Analysis and Weight Optimization of Knuckle joint for different Materials by using CAE Tools

The current study involved the analysis of a knuckle joint using finite elements. A mechanical joint with two intersecting cylindrical rods whose axes are in the same plane is called a knuckle joint. Knuckle joint should be designed and manufactured in such a way that it can sustain more load without failure. The objective of the present study is to study knuckle joints made of different materials like aluminum, stainless steel, structural steel, magnesium, and gray cast iron using CAE tools. The CAD model of knuckle joint is made in CATIA V5 R20. The finite element analysis of this CAD model using ANSYS 15 has been carried out to investigate maximum stress and deformation. The CAE results compared with the analytical results using conventional approach. The CAE results have been found close to the analytical results, thus validating the model. The knuckle joint of aluminum is found to have highest factor of safety (1.641) at 50 KN load and is the most the most suitable material for knuckle joint. Weight of vehicle plays an important role in overall performance and fuel efficiency of vehicle. Knuckle joint is a part of vehicle. Hence weight optimization of knuckle joint made of aluminum has been performed using ANSYS 15 and it is observed that weight of knuckle joint made of aluminum can be reduced by 5.08% for 50 KN loading condition. Key Words: Knuckle joint, Finite element analysis, Mechanical joint, Load-bearing capacity, Material selection, CAE tools, Deformation analysis etc.

Finite Element Analysis and weight Optimization of Knuckle joint for different materials by using CAE Tools

The current study involved the analysis of a knuckle joint using finite elements. A mechanical joint with two intersecting cylindrical rods whose axes are in the same plane is called a knuckle joint. Knuckle joint should be designed and manufactured in such a way that it can sustain more load without failure. The objective of the present study is to study knuckle joints made of different materials like aluminum, stainless steel, structural steel, magnesium, and gray cast iron using CAE tools. The CAD model of knuckle joint is made in CATIA V5 R20. The finite element analysis of this CAD model using ANSYS 15 has been carried out to investigate maximum stress and deformation. The CAE results compared with the analytical results using conventional approach. The CAE results have been found close to the analytical results, thus validating the model. The knuckle joint of aluminum is found to have highest factor of safety (1.641) at 50 KN load and is the most the most suitable material for knuckle joint. Weight of vehicle plays an important role in overall performance and fuel efficiency of vehicle. Knuckle joint is a part of vehicle. Hence weight optimization of knuckle joint made of aluminum has been performed using ANSYS 15 and it is observed that weight of knuckle joint made of aluminum can be reduced by 5.08% for 50 KN loading condition. Key Words: Knuckle joint, Finite element analysis, Mechanical joint, Load-bearing capacity, Material selection, CAE tools, Deformation analysis etc.

Characteristics of VE/HXLPE wear particle morphology: A comparative analysis with UHMWPE in an in vitro artificial tibial insert simulation test

Particle generation from artificial knee prostheses is a leading cause of artificial joint failures. Vitamin E stabilized highly cross-linked polyethylene (VE/HXLPE) is known for its antioxidant properties and minimal wear characteristics. However, research on the wear behavior of VE/HXLPE is limited. This study aims to compare wear debris from VE/HXLPE with the conventional material Ultra High Molecular Weight Polyethylene (UHMWPE) under identical in vitro test conditions. Specifically, Principal Component Analysis (PCA) was employed to morphologically categorize particles, resulting in four distinct groups for VE/HXLPE and five for UHMWPE. Notably, 68 % of VE/HXLPE particles exhibited small-sized spheroidal morphology, while UHMWPE mainly produced elongated bioactive particles. Key particle attributes were then assessed, including 'equivalent circle diameter (ECD)', 'aspect ratio (AR)', and 'roundness (R) ', and presented as frequency distributions. The morphological analysis revealed that VE/HXLPE particles displayed various shapes, such as spheroidal, flakes, bulks, rods, and fibrils, and their formation mechanism was discussed. Additionally, the Functional Biological Activity (FBA) of VE/HXLPE wear particles was calculated. The results demonstrated differences in particle sizes, shape distributions, and bioactivity between VE/HXLPE and UHMWPE, which indicates that VE/HXLPE particles had a lower likelihood of inducing osteolysis. This study holds promise for gaining deeper insights into the mechanical properties and the potential for bioactivity in VE/HXLPE as an artificial joint material.