Von Mises Stress Research Articles

Material Selection for Differential Gearbox under Torque Conditions: A Simulation-Based Study

Abstract: This research paper conducts an in-depth exploration into the structural behaviors of three distinct materials—Cast Iron, Copper Alloy, and Magnesium Alloy—within the framework of a differential gearbox under varying torque loads. Employing finite element analysis through ANSYS, the investigation systematically scrutinizes critical parameters such as total deformations, equivalent stress (von Mises stress), and shear stress. The primary aim is to offer insights that guide material selection strategies and enhance the optimization of design processes in automotive applications. The results illuminate nuanced material responses when exposed to torque conditions, presenting implications for real-world gear assembly scenarios. This study significantly contributes to the evolving knowledge base in automotive engineering, providing a foundation for wellinformed decision-making in material selection and design optimization for differential gearboxes.

A Biomechanical Comparison of 2 Different Topping-off Devices and Their Influence on the Sacroiliac Joint Following Lumbosacral Fusion Surgery.

Interspinous spacer (ISS)-based and pedicle screw-rod dynamic fixator (PDF)-based topping-off devices have been applied in lumbar/lumbosacral fusion surgeries for preventing the development of proximal adjacent segment degeneration. However, little attention has been paid to sacroiliac joint (SIJ), which belongs to the adjacent joints. Accordingly, the objective of this study was to compare how these 2 topping-off devices affect the SIJ biomechanics. A validated, normal finite-element lumbopelvic model (L3-pelvis) was initially adjusted to simulate interbody fusion with rigid fixation at the L5-S1 level, and then the DIAM or BioFlex system was instrumented at the L4-5 level to establish the ISS-based or PDF-based topping-off model, respectively. All the developed models were loaded with moments of 4 physiological motions using hybrid loading protocol. Compared with the rigid fusion model (without topping-off devices), range of motion and von-Mises stress at the SIJs were increased by 23.1%-64.1% and 23.6%-62.8%, respectively, for the ISS-based model and by 51.2%-126.7% and 50.4%-108.7%, respectively, for the PDF-based model. The obtained results suggest that the PDF-based topping-off device leads to higher increments in SIJ motion and stress than ISS-based topping-off device following lumbosacral fusion, implying topping-off technique could be linked to an increased risk of SIJ degeneration, especially when using PDF-based device.

Biomechanical analysis and comparison between ‘Zeta’ miniplate design and conventional miniplate system for fixation of fracture segments in transition zone of parasymphysis body region of mandible – an in vitro study

The parasymphysis area of the mandible is highly dynamic because it is subjected to both occlusal and muscular forces. As a result, the fractures in this transition zone have a special pattern, posing a challenge for surgeons whether to use one miniplate versus two miniplates, as per Champy's recommendations. The commonest complication resulting to treat this area is mental nerve paraesthesia due to the dissection and stretching of the nerve. Hence, an in vitro research study of a newly designed ‘Zeta’ miniplate is performed, to evaluate the biomechanical behaviour using finite element (FE) analysis and biomechanical analysis along with a comparison study with the conventional miniplate configurations. The results showed that the Zeta miniplate produces the lowest stresses 17.511 MPa and the least total structural deformation of 0.0011 mm after applying the maximum occlusal bite force. On application of torsional load, total structural deformation was 0.0004 mm and von Mises (VM) stress value was 0.24 MPa which was lowest when compared with the two miniplate system. Hence, the newly developed Zeta miniplate is superior in terms of stability. Another benefit of its design is that it helps in preventing mental nerve paraesthesia and tooth root damage while fixing and stabilising the fractured bony segments.

Uncertainty Factors of a Finite Element Model using the Fuzzy Analysis Method

The recent advancement in manufacturing technology in the automotive and aerospace sectors has led to the invention of advanced structured material, which is lightweight and a complex geometry model that can be manufactured. As it is related to human safety and hazards, the need for uncertainty analysis in a structure before and after a manufacturing process is a primary concern. Thus, this paper analyzes the uncertainty parameters of a meshed finite element model in the geometry, boundary condition, load, and material properties. An uncertainty analysis numerical tool, the fuzzy analysis method, is applied in Excel-VBA as the simulation platform. Each uncertainty parameter is in a range of numbers, with a maximum and minimum value as the limit. The α-cuts determine the fuzzy analysis output on the membership function. The deterministic value of the variable is implemented for comparison purposes. The simulation result for the von-Mises stress analysis has significantly impacted the uncertainty analysis as its curve has surpassed the yield strength limit of the material. The simulation output for the displacement has a more considerable uncertainty dispersion when compared to the other results. This study helps to find a better security margin of a structure for its sustainability in the future.

Variation of infrastructure materials in prostheses on pontic implants and their effect on the dissipation of Von Mises stresses in implants and components

The configuration of fixed partial dentures with a suspended or pontic intermediate element, associated with the use of 2 implants at their ends, is usually found clinically. In a situation with a smaller number of implants supporting an eventual 3-element prosthesis, there is a greater biomechanical demand on the entire system. A possible option to reduce the stresses disseminated to the implants and components is to vary the prosthesis infrastructures. Therefore, the objective of this study was to verify and compare the stresses developed on the implants and components according to the variation of the materials of the infrastructures of the prostheses on implants. The von Mises Equivalent Stresses (VMES) were analyzed for quantitative and qualitative assessment of the areas of greatest biomechanical demand. The experimental groups were varied according to the infrastructure used: Acrylic resin (AR), Lithium disilicate (LD), Type IV gold (Au), Titanium (Ti), Nickel-Chromium (NiCr), Cobalt-Chromium (CoCr) and Zirconia (Zr). The methodology used was the Finite Element Method (FEM), with simulations by the Ansys Workbench 10.0 software program. The results obtained allowed observing that, according to the variation of the material used in the prosthesis, there are different stresses generated in the analyzed ductile structures (implants and components). It can generally be concluded that an inversely proportional relationship was found between the stiffness of the infrastructure material and the stresses generated in the implants and components. Thus, more rigid infrastructures are capable of transmitting less stress to the implants and their components, which would be characterized as the best option in order to preserve the implants and components that are closer to the supporting bone.

The Influence of Reverse Yielding on the Plastic Conditioning of Interference Fits in Power Transmission Engineering

Interference fits are very common shaft–hub connections due to their low manufacturing costs and excellent technical properties. The Plastic Conditioning of this machine element is a new and not very well-known method. During the development of this method, it was discovered that Reverse Yielding occurs in certain applications and has a negative impact on the result. This paper examines the effects of Reverse Yielding on the technology of Plastic Conditioning of interference fits in Power Transmission Engineering. Based on the Shear Stress Hypothesis (SH), the Plane Stress State (PSS), and the ideal plastic behavior of materials, established stress–mechanical relationships are used to find the influencing parameters of Reverse Yielding on the technology of Plastic Conditioning and their limits. As a result, a new computational concept is developed that allows the user to maximize Plastic Conditioning while avoiding Reverse Yielding. Analytical calculation suggestions and diagrams for practical application are provided. Furthermore, the deviations in the obtained results, taking into account other material models such as the Von Mises Yield Criterion (VMYC) and material hardening, as well as the Bauschinger effect, are examined in comparison with our own numerical results from the development of Plastic Conditioning, and the resulting need for further research is defined. In addition, the method of Plastic Conditioning of interference fits is introduced and its basic principles are briefly explained.

Numerical simulation of the bentonite-bonded sand mould compaction process using micro-mechanical parameter relationships

ABSTRACT Commercial software packages for FEM analysis have been used to numerically simulate the behaviour of the complex systems of bentonite-bonded sand mould under pressure and subjected to stress distributions and to predict their performance. The Drucker-Prager model and the Mohr-Coulomb model are two well-known mathematical models used to describe the plastic non-linear behaviour of the soil. Conducting direct shear tests on varying densities of sand can provide the individual parameters necessary for the simulation of the moulding process. A new approach is based on making relationships between micro-mechanical parameters and changes in sand density during the compaction process. COMSOL Multiphysics is a popular software tool used to implement FEM simulations. The steps involved drawing geometry, inserting material properties, mesh generation and time-dependent density, and solving the model. The boundary conditions depend on the particular problem being analysed, which defines the external forces and constraints acting on the structure. The use of a coarse mesh and stationary study may be a computationally efficient approach for the evaluation of the compaction process of green sand. The study found that the maximum displacement value is 6.1*10−3 mm, the maximum volumetric strain value is 8.88*10−5, and the von Mises stress is 4.14*103 N/m2.

Modeling and Simulation of Elastohydrodynamic Lubrication in Spur Gears

An analysis using computational modeling by finite elements of the phenomenon of elastohydrodynamic lubrication (EHL) was carried out for a transmission system of pinion gear in a crankcase with partial filling lubrication. The analysis utilized tribological studies describing the contact behavior characteristics of solid surfaces with the lubrication film caused by dragging and splashing. Furthermore, the characteristics of the Reynolds-Hertz model for this type of phenomena are described, as well as the equations of elastic deformation and elastic displacements along with the geometry of the non-concordant bodies in contact. This was done by modeling the Lagrangian-Eulerian type for non-Newtonian fluid, implementing multiphysics coupling methods. The pressure profile of the lubricant films, the temperature reached by the lubricant, and the von Mises stress at the contact were obtained, showing a good approximation with the related results, indicating a range of 30 MPa to 900 MPa of pressure in the lubricant film and von Mises stress ranging from 30 MPa to 100 MPa in the contact area of the gear tooth.

Bio-mechanical effects of femoral neck system versus cannulated screws on treating young patients with Pauwels type III femoral neck fractures: a finite element analysis

IntroductionAs a novel internal fixation for femoral neck fractures, the femoral neck system has some advantages for young Pauwels type III femoral neck fractures without clear biomechanical effects and mechanisms. Thus, the objection of the study is to realize the biomechanical effects and mechanism of FNS cannulated screws on treating young patients with Pauwels type III femoral neck fractures compared to cannulated screws which are commonly used for femoral neck fractures by finite element analysis.MethodsFirstly, the model of young Pauwels type III femoral neck fractures, femoral neck system (FNS), and three cannulated screws (CS) arranged in an inverted triangle were established, and the internal fixations were set up to fix young Pauwels type III femoral neck fractures. Under 2100 N load, the finite element was performed, and the deformation, peak von Mises stress (VMS), and contact at fracture segments were recorded to analyze the biomechanical effects and mechanism of FNS and three-CS fixing young Pauwels type III femoral neck fractures.ResultsCompared to three-CS, the deformation of the whole model, internal fixation, and fracture segments after FNS fixation were lower, and the peak VMS of the whole model and the internal fixation after FNS were higher with lower peak VMS of the distal femur and the fracture segments. With a sticking contact status, the contact pressure at fracture segments after FNS fixation was lower than that of three-CS.ConclusionsFNS can provide better mechanical effects for young patients with Pauwels type III femoral neck fractures, which may be the mechanical mechanism of the clinical effects of FNS on femoral neck fracture. Although there is high stress on FNS, it is still an effective and safe internal fixation for young patients with Pauwels type III femoral neck fractures.

Investigating the Influence of Holes as Crack Arrestors in Simulating Crack Growth Behavior Using Finite Element Method

The primary focus of this paper is to investigate the application of ANSYS Workbench 19.2 software’s advanced feature, known as Separating Morphing and Adaptive Remeshing Technology (SMART), in simulating the growth of cracks within structures that incorporate holes. Holes are strategically utilized as crack arrestors in engineering structures to prevent catastrophic failures. This technique redistributes stress concentrations and alters crack propagation paths, enhancing structural integrity and preventing crack propagation. This paper explores the concept of using holes as crack arrestors, highlighting their significance in increasing structural resilience and mitigating the risks associated with crack propagation. The crack growth path is estimated by applying the maximum circumferential stress criterion, while the calculation of the associated stress intensity factors is performed by applying the interaction integral technique. To analyze the impact of holes on the crack growth path and evaluate their effectiveness as crack arrestors, additional specimens with identical external dimensions but without any internal holes were tested. This comparison was conducted to provide a basis for assessing the role of holes in altering crack propagation behavior and their potential as effective crack arrestors. The results of this study demonstrated that the presence of a hole had a significant influence on the crack growth behavior. The crack was observed to be attracted towards the hole, leading to a deviation in its trajectory either towards the hole or deflecting around it. Conversely, in the absence of a hole, the crack propagated without any alteration in its path. To validate these findings, the computed crack growth paths and associated stress intensity factors were compared with experimental and numerical data available in the open literature. The remarkable consistency between the computational study results for crack growth path, stress intensity factors, and von Mises stress distribution, and the corresponding experimental and numerical data, is a testament to the accuracy and reliability of the computational simulations.

Stress analysis of horizontal mid-root fracture managed with different intraradicular fixation protocols: A 3D-finite element study.

The current study evaluated the stress distribution in a maxillary central incisor with mid-root fracture after splinting with different intra-radicular posts using 3D-finite element analysis (FEA).Five 3D-FEA models were constructed. Model 1 was an intact tooth with no fracture, Model 2: A tooth with a horizontal mid-root fracture, with no treatment. Model 3: Same as model 2, and intraradicular splinting using fiber post. Model 4: Same as model 2 and intra-radicular splinting using Protaper Gold file F3. Model 5: Same as model 2, and with intraradicular splinting with Ribbond. The FEA of all models was done to obtain the maximum Von-Mises stress in the root canal space, the dentin, the periodontal ligament, and the bone. The highest Von Mises stresses for the root canal space and the dentin were found in Model 3, followed by models 4, 5, and 2, and least in Model 1. The Von Mises stress of the periodontal ligament was the least in model 1. The Von Mises stress of bone was higher in all experimental models than in the baseline model. The results suggest that in cases where intra-radicular splinting is indicated, fiber posts and Ribbond are better alternatives to endodontic files due to the lower stresses exerted.

Patient-specific mechanical analysis of PCL periodontal membrane: Modeling and simulation

This research fills a knowledge gap in bone tissue engineering by examining the mechanical characteristics of scaffolds at bone-tissue interfaces utilizing a cutting-edge technique involving the creation of 3D scaffolds from Polycaprolactone (PCL). The work employs Finite element analysis to measure the scaffolds' maximum principal and Von Mises stresses and strains. CT scans of the Maxilla and Mandible were used to apply load conditions to 3D models of the upper central incisor. In the derived computational model, four different load situations considered were: the masticatory load (70–100 N at 45°), two parafunctional habits (100–130 N) and 500–550 N at the incisal edge, both at 45°), and a trauma case (800–850 N applied perpendicularly from the inwards direction at 90°). The findings revealed that the central tooth region experiences the highest stress concentration, while the Maxilla and Mandible regions show the least stress. These results provide critical insights into the mechanical behavior of scaffolds at bone-tissue interfaces, suggesting a research direction for developing scaffolds that closely mimic real bone characteristics. The results of this study are particularly significant for using bone replacement materials, providing an approach to more effective healing options for bone traumas and degenerative bone disorders.

An enhanced DPC model for metal powder incorporating yield strength of solid-state

The Drucker-Prager/Cap (DPC) Model has a significant drawback in metal powder metallurgy simulations, which is the potential for the von Mises stress to exceed the yield strength of the solid state. To address this issue, this paper introduces a novel hardening law that effectively restricts the von Mises stress within the yield strength of solid alloy. As the powder becomes denser, the yield surface of the DPC model gradually approach towards the von Mises yield surface. To validate the proposed model, both micro-scale finite element simulations and published experimental data were used. The effectiveness of the proposed model was demonstrated through its application in the simulation of two scenarios: cold die compaction of aluminum powder and hot isostatic pressing of a Nickel based superalloy. The results indicate that the proposed model outperforms the original DPC model and is more suitable for powder metallurgy simulations.

Study on the Ultimate Load Failure Mechanism and Structural Optimization Design of Insulators.

This study aims to enhance the productivity of high-voltage transmission line insulators and their operational safety by investigating their failure mechanisms under ultimate load conditions. Destructive tests were conducted on a specific type of insulator under ultimate load conditions. A high-speed camera was used to document the insulator's failure process and collect strain data from designated points. A simulation model of the insulator was established to predict the effects of ultimate loads. The simulation results identified a maximum first principal stress of 94.549 MPa in the porcelain shell, with stress distribution characteristics resembling a cantilever beam subjected to bending. This implied that the insulator failure occurred when the stress reached the bending strength of the porcelain shell. To validate the simulation's accuracy, bending and tensile strength tests were conducted on the ceramic materials constituting the insulator. The bending strength of the porcelain shell was 100.52 MPa, showing a 5.6% variation from the simulation results, which indicated the reliability of the simulation model. Finally, optimization designs on the design parameters P1 and P2 of the insulator were conducted. The results indicated that setting P1 to 8° and P2 to 90.062 mm decreased the first principal stress of the porcelain shell by 47.6% and Von Mises stress by 31.6% under ultimate load conditions, significantly enhancing the load-bearing capacity. This research contributed to improving the production yield and safety performance of insulators.

Polishing-induced material attrition in surface-texturing AlN using a nanoscale polishing tool: An atomic-scale understanding

This study examines the alterations in the material properties and the effectiveness of the nano-polishing process applied to the surface of AlN substrate material through molecular dynamics simulations. Various controlled parameters at the outset of the polishing process, including polishing depth, polishing speed, and surface texture, exert both positive and negative influences on substrate characteristics, such as polishing force, friction coefficient, atomic phase transformation, subsurface damage layer (SDL), von Mises stress, temperature, dislocation characteristics, surface topography, atom removal, and root-mean-square (RMS). The results depicted that great polishing depth and slow polishing velocity have adverse effects on the internal structure of the material, leading to the creation of a substantial SDL and a dense network of dislocation formation. Conversely, increased material polishing velocity results in elevated von Mises stress and high generated temperatures. When combined with the initial surface structure conditions of the material, this mitigates detrimental effects on the internal structural characteristics while facilitating the phase transformation process and enhancing atom removal efficiency. The calculated RMS results of the substrate demonstrate that adjustments in polishing speed yield a higher improvement in surface roughness compared to alterations in polishing depth and surface texture. Therefore, a comprehensive understanding of the impact of initial conditions in the polishing process, as well as the atomic-level surface structure of the substrate, aids in selecting the most appropriate polishing conditions to produce the highest-quality products.

Influence of internal angle and shape of the lining on residual stress of Class II molar restorations

Polymerization shrinkage is a major side effect of resin composite materials that affects the success and longevity of caries restorations. This study was to analyze the effect of the internal angle and shape of the lining on the shrinkage residual stress of dental restorations in Class II mesio-occlusal-distal (MOD) cavities through finite element analysis (FEA). A 3D reconstructed model of a human mandibular first molar was created from micro-CT images, and then the tooth was prepared as a Class II MOD cavity. 3D models of four regular internal corner shapes of Class II MOD cavities with different internal angles of lining and one 90° filleted corner model were created. The thermal expansion technique was applied to approximate the shrinkage impact of composite resin polymerization in the FE software ABAQUS. Von Mises stress was taken as a metric. The results showed that the level of residual stresses in the Class II MOD cavities was greatly dependent on the internal angle of the lining. The maximum von Mises stress in tooth tissue decreased as the internal angle of the lining increased. The internal shapes of the lining had no obvious effect on the stress, and the filleted corner model had less stress. This lining strategy is appropriate for Class II MOD cavities with serious loss of tooth tissue.

Characterizing the mechanical deformation response of AHSS steels: A comparative study of cyclic plasticity models under monotonic and reversal loading

This study evaluates the performance of a user-defined combined hardening modeling method for advanced high-strength steels (AHSS) under monotonic and reversal loading conditions. The plastic behavior of TWIP980 and TRIP980 AHSS sheet metals is investigated using a cyclic plasticity modeling approach. The model incorporates an isotropic von Mises yield criterion and a single-term Chaboche nonlinear kinematic hardening rule. Monotonic and reversal loading stress-strain curves are predicted and compared with experimental results. The model accurately captured the Bauschinger effect for both materials, but it needs help to effectively model the permanent softening behavior observed in TWIP980 steel. Overall, the proposed modeling method agrees well with experimental results for monotonic loading and accurately represents the Bauschinger effect and transient behavior during reversal loading. However, better improvements are needed to capture the permanent softening behavior of TWIP980 steel.

Analysis of the Effect of Thread Depth in Four Different Thread Designs on the Stress Distribution at the Implant-bone Interface Using Finite Element Analysis – A Comparative Three-Dimensional In vitro Study

ABSTRACT Statement of Problem: Treatment with dental implants owes much of its success to the development and maintenance of an osseointegrated bone-implant interface. The development of this interface is influenced by various factors, of which implant thread design plays a dominant role. Purpose: The purpose of this study is to analyze the effect of thread depth in four different thread designs on the stress distribution at the implant-bone interface using three-dimensional finite element analysis. Materials and Methods: Four implant models with different thread shapes, namely V thread, square thread, buttress thread, and reverse buttress thread with an uniform thread depth of 0.4 mm were designed. These models were then placed in the mandibular first molar region. Force of 100 N was applied axially and at 45°angle to the implant. Von Mises stress was measured at the implant – Bone interface area and compared for the different designs. Results: The color plots obtained were studied and the maximum Von Mises stress was noted and tabulated for each condition. Stress distribution in the finite element models comes in the numerical values and in color coding. Maximum values of Von Mises stress are denoted by red color and minimum value by blue color. In between, the values are represented by bluish green, green, greenish yellow, and yellowish red in the ascending order of stress distribution. Conclusion: Thread design plays an important role in stress distribution in implant and bone. Varying Von Mises stress is seen at the cortical bone-implant and cancellous bone-implant interface. Clinical Implication: Successful osseointegration is necessary for implant success and thread design plays a very important role in osseointegration. Therefore, the selection of implants with proper thread design contributes greatly to the success of an implant-retained prosthesis.

Sacrolumbar Interbody Fusion (SLIF): Feasibility, Technical Nuances, Biomechanical Assessment, and Clinical Outcomes.

S1-L5 transdiscal screw fixation is a direct stabilization technique used for surgical treatment of high-grade (III-IV) L5-S1 spondylolisthesis. It has not been used for nonspondylolisthetic cases or in combination with an interbody cage (IC). This study aimed to develop a novel, direct S1-L5 sacrolumbar interbody fusion (SLIF) technique, a combination of IC and sacrolumbar transdiscal screw. SLIF was tested in cadaveric, clinical, and finite element analysis settings. Three cadaveric lumbar spines were used to test the SLIF procedure before clinical application. Eight patients underwent the SLIF procedure. Clinical outcomes were evaluated by visual analog score for leg and back pain, short form 36, Oswestry disability index, and neurological examination. CT scans of the lumbar spine were used to assess the hardware placement and subsequent fusion. Finite element analysis was performed on a healthy human CT-based L5-S1 model. Intact segment, unilateral facetectomy and discectomy, SLIF, and transforaminal lumbar interbody fusion (TLIF) procedures were compared in terms of the range of motion (ROM), von Mises stress on hardware, and shear-induced directional deformity. Additionally, the same set of tests were conducted in an osteoporotic model. Excellent hardware placement was feasible in three cadavers and eight patients. Preoperative neurological deficits improved in all patients. Statistically significant improvements were obtained on all self-reported questionnaire scores. All patients developed solid, Bridwell grade I fusions. Biomechanical testing revealed similar outcomes for TLIF and SLIF regarding the ROM. However, the screw's von Mises stress and shear-induced directional deformity were low for SLIF of healthy and osteoporotic bone. SLIF is a feasible, safe, and effective L5-S1 fusion option suitable for all clinical scenarios. It provides several biomechanical advantages, yielding excellent clinical outcomes.

Analiza elastično-plastičnog naprezanja skupljajućih debelih FGM cilindara

This paper addresses the stress analysis of shrink-fitted thick-walled cylinders made of functionally graded material (FGM). Analytical solutions are provided for the elastic-plastic behavior of shrink-fitted axisymmetric thick-walled FGM cylinders based on the linear plane elasticity theory and plasticity laws. Due to the material's functional gradation, mechanical characteristics like Young's modulus, yield stress, and plastic parameters are controlled by a power function along the wall thickness. Considering a plane strain case, elastic-perfectly plastic model and Von Mises yield criterion; theoretical solutions are obtained for both elastic and plastic phases. The radial, hoop, axial, and equivalent Von Mises stresses are obtained for up to 25%, 50%, and 75% of cylinder plasticization for the elastic and plastic zones. Stresses are given in terms of interference and geometrical and mechanical parameters of the assembly. In addition, the interferences to start plastic deformation and the full plastic collapse of the cylinder are discussed. Moreover, the effect of the gradient index on the contact pressure and both the start of yield and plastic collapse pressures are conducted. The analytical results found in the current research are compared with the numerical solutions carried out by Ansys Workbench. Both results show a good agreement.