Finite Element Stress Analysis Research Articles

Evaluation of stress distributions in endodontically treated anterior incisors under occlusal and trauma-induced forces following various restoration treatments: A finite element analysis.

The aim of this study was to calculate the stress distribution of fiberglass post associated with resin composite crown restoration and fiberglass posts with zirconia restorations in mature and immature endodontically treated central maxillary incisor under various loading conditions. The study created six different study models in a virtual environment: healthy mature maxillary central teeth, intact immature maxillary central teeth, mature maxillary central teeth with fiberglass post associated with resin composite crown restoration, immature maxillary central teeth with fiberglass post associated with resin composite crown restoration, mature maxillary central teeth with fiberglass posts and zirconia restoration, and immature maxillary central teeth with fiberglass posts and zirconia restoration. Loading conditions simulating mastication, trauma, and bruxism were applied to each of the models at different angles and amounts. The von Mises and the maximum and minimum principal stress values in tooth structures (dentin) and support structures (bone, PDL) and materials were observed using finite element stress analysis. The highest stress values in the tissue and the restoration structure were observed for masticating force and crowns rehabilitated with zirconia restorations. None of the compared loading conditions and restorations showed destructive stress values on periodontal ligament or bone. The mature and immature endodontically treated central maxillary incisors can be better rehabilitated using fiberglass post associated with resin composite crown restoration and may be preferred to zirconia restorations in order to reduce the stresses on the surrounding tissues and teeth. However, further clinical studies are needed to fully explore this topic.

Evaluation of stress distribution of different marginal designs on PEEK and PEKK substructure materials, cortical and cancellous Bone:A finite element analysis

High-performance polymers are used in different fixed prosthesis treatments due to their many advantages such as biocompatibility, shock absorption ability, high fracture resistance. The effects of marginal design on the forces on high-performance polymers are unknown. This study aimed was to investigate the stress distribution of different marginal designs on Polyetheretherketone (PEEK) and Polyetherketoneketone (PEKK) substructure materials, cortical bone and cancellous bone by finite element analysis. A first maxillary molar tooth was modeled in 3D using the "3D Complex Render" method. Considering the ideal preparation conditions (Taper angle was 6°, step depth was 1 mm, occlusal reduction was 2mm), four different configurations were modeled by changing the marginal design (chamfer, deep chamfer, shoulder 90°, shoulder 135°). PEEK, PEKK substructure, and composite superstructure were designed on created models. A total of 150N oblique force from two points and a total of 300N vertical force from three points were applied from occlusall. and the maximum principal stress, minimum principal stress, von Mises stress findings in the cortical bone, spongiose bone, and substructure were examined. The study was carried out by static linear analysis with a three-dimensional finite element stress analysis method. The highest maximum principal stress value in the cortical bone was observed when the PEEK+Shoulder 135° step at vertical force. The highest minimum principal stress value in the cortical bone was observed when the PEEK+Shoulder 90° step, and PEEK+deep chamfer step at oblique force. The highest maximum principal stress value in spongiose bone was observed when the PEEK+Shoulder 90° step. The highest minimum principal stress value in spongiose bone was observed when the PEEK+deep chamfer step at vertical force. The highest von Mises stress value in the substructure was observed when the PEKK+Deep chamfer step at oblique force. The lowest maximum principal stress value in the cortical bone was observed when the PEKK+Shoulder 135° step at oblique force. The lowest minimum principal stress value in the cortical bone was observed when the PEEK+Shoulder 135° step, and PEKK+shoulder 135° step at vertical force. The lowest maximum principal stress value in spongiose bone was observed when the PEEK+Shoulder 90° step. The lowest minimum principal stress value in spongiose bone was observed when the PEEK+Shoulder 135° step and PEKK+Shoulder 135° step at vertical force. The lowest von Mises stress value in the substructure was observed when the PEEK+Deep chamfer step at vertical force. When cortical and spongiose bone stress were evaluated, no destructive stress was observed. Considering the stresses occurring in the substructure the highest stress was observed in the chamfer step.

Finite element stress analysis of nano copper-based anti-friction coating for improved threaded connections in petroleum drilling tools

Threaded connections are commonly used in connecting petroleum drilling tools (PDTs). In this study, we use nano copper (NaCU) and epoxy-resin binder to prepare a NaCU-based anti-friction coating (NaCU-AFC). Furthermore, we use finite element analysis (FEA) to validate torque and pressure distribution on the contact tooth surface of threaded joints of PDTs. The results demonstrate that the NaCU-AFC can effectively reduce torque by 35.66%, and significantly improve anti-sticking performance, thereby extending the service life of PDTs. In summary, this study provides valuable insights for practical applications in coating processes for PDTs.

Finite element stress analysis in mandibular molars with apical root resorption and crown destruction after root canal treatment using various materials

Aim: The objective of this study is to analyze the stress distribution of root canal treated teeth under occlusal forces and aid in the selection of appropriate materials for teeth with root tip resorption and crown destruction, using the finite element stress analysis method (FEM). Methods: The study was conducted on two-rooted lower molar teeth, divided into five groups. The root length was 14 mm, the crown length was 7.5 mm, and the total length was 21.5 mm. It was assumed that the distal canals were resorbed by 4 mm. Group 1 consisted of untreated intact teeth. Group 2 involved filling the mesial canals with gutta-percha, filling the apical part of the distal canal with 4 mm Mineral Trioxide Aggregate (MTA), and fabricating the crown using glass fiber post and IPS e.max materials. Group 3 involved filling the mesial canals with gutta-percha, filling the apical part of the distal canal with 4 mm Biodentin, and manufacturing the crown using glass fiber post and IPS e.max materials. Group 4: The canals were filled with MTA, and an IPS e.max endocrown was used. Group 5: The canals were filled with Biodentin and an IPS e.max endocrown was used. The study examined the effect of a 100 Newton force applied in the occlusal direction on dental tissues using finite element stress analysis. Results: The study found that the application of fiber posts resulted in less stress accumulation in tooth tissues compared to endocrown. Conclusion: The use of Biodentin or MTA in endocrown teeth did not affect the stress in tooth tissues caused by applied force. In conclusion, while fiber posts increase durability by reducing stress in root-end resorbed teeth, the effect of Biodentin or MTA on stress resistance in dental tissues is limited. How to cite this article: Duran S, Şirin DA, Topbaş C. Finite element stress analysis in mandibular molars with apical root resorption and crown destruction after root canal treatment using various materials. J Med Dent Invest 2024;5:e240320. https://doi.org/10.5577/jomdi.e240320

Size effects of voids on the mechanical properties of 3D printed parts

Although the effects of additive manufacturing process parameters on the mechanical properties of 3D printed parts have been numerically investigated in the literature, less attention has been paid on the size effects of voids between deposited filaments. This study fills this gap by developing a methodology based on a combined finite element (FE) and design of experiment (DoE) technique. The development of FE methodology is based on micro-mechanical analysis of representative volume element (RVE) of 3D printed parts to predict the effective orthotropic properties. To account for the size effects of inter-bead voids, the RVE includes contribution of the multiple parameters of layer heights, layer widths and overlapping regions. To study the main and interaction effects of the above input parameters on the stiffness properties of 3D printed parts, a structured approach based on full factorial design is used. Although the size effects of voids on the constituents of elastic moduli of RVE were investigated, the main focus in the present work is to develop a regression model to predict the stiffness properties. The FE stress analysis of the RVE conducted in this study provides an insight about the potential failure modes such as delamination and filament debonding that may occur in load bearing 3D printed parts. For a case study, the results of FE-based homogenization technique in terms of stiffness properties are validated against the experimental data via three-point bending and Iosipescu shear tests which were conducted in conjunction with digital image correlation technique. The combined numerical and statistical approach proposed in this study provides a swift iterative design of 3D printed parts prior to the time-consuming computation modelling, contributing to reduce the number of tests and manufacturing costs.

Investigation of the effects of volume fraction, aspect ratio and type of fibres on the mechanical properties of short fibre reinforced 3D printed composite materials

AbstractMechanical behaviour of 3D-printed composite parts is affected by the volume fraction, aspect ratio and type of fibre reinforcement. Although in the literature experimental approaches have been used to characterise the effects of the above factors on the mechanical properties of 3D printed parts, time and cost of the manufacturing process as well as the uncertainty associated with a large number of experimental techniques are the key issues. This study aims to address these challenges by developing a methodology based on a multi-scale Finite Element (FE) analysis of representative volume element (RVE) of 3D printed composite parts to predict the effective orthotropic properties. To account for the effects of fibre features, RVEs were modelled considering variables of volume fraction, aspect ratios and type of short fibres. To study the main and interaction effects of the above variables on the mechanical properties of 3D printed composite parts, a structured approach based on the Design of Experiments is used. The FE stress analysis of the RVE provides an understanding about the potential failure modes such as interfacial debonding between fibres and matrix, interlayer and intralayer delamination that may occur in load-bearing 3D printed composite parts. The FE computed mechanical properties are validated against experimental data through a series of mechanical testing of flexure, Iosipescu, and short beam shear which were conducted in conjunction with the Digital Image Correlation technique. As a result, certainty is obtained in using the proposed approach for a fast iterative design of 3D printed composite parts prior to industrial applications.

Finite element stress analysis and topological optimization of a commercial aircraft seat structure

In recent years, the Finite Element Method (FEM) has emerged as a cornerstone in the field of seating design, particularly within the aircraft industry. Over the past decade, significant advancements in Finite Element (FE) analysis techniques have revolutionized the seat industry, enabling the creation of safer and more cost-effective seat designs. The accuracy of FE analysis plays a pivotal role in this transformation. In the process of constructing a reliable finite element model, the selection and precise manipulation of key parameters are paramount. These crucial parameters encompass element size, time scale, analysis type, and material model. Properly defining and implementing these parameters ensures that the FE model produces accurate results, closely mirroring real-world performance. Verification of Finite Element Analysis (FEA) results is commonly accomplished through experimental methods. Notably, when the parameters are appropriately integrated into the modelling process, FE analysis outcomes closely align with experimental results. This study aims to leverage the power of FEM in performing static stress analysis and topology optimization of aircraft seats using the SOLIDWORKS commercial finite element platform. By simulating loading conditions, this research calculates static stresses and displacements experienced by the aircraft seat. Through a comprehensive topology optimization study, the weight of the airplane seat is remarkably reduced by up to 30%, while still prioritizing passenger safety. The success of this optimization showcases the potential for substantial weight savings in aircraft seat design without compromising safety standards.

Evaluating Angled Abutments: Three-Dimensional Finite Element Stress Analysis of Anterior Maxillary Implants

Restorative dentistry is the repairing of damaged teeth and restoring oral health and function. Dental implants are typically placed within the cortical bone of the jaw to provide stability and support for prosthetic restorations. The successful restoration of complex anatomical features of the maxillary anterior is difficult for prosthodontists. Using a 3D slicer, CT scan images were used to create a detailed three-dimensional model of the maxilla bone. This study utilizes ANSYS Workbench, a finite element software program, to analyze the abutment angles, ranging from 0° to 25°, and the impact stress distribution within peri-implant bone. The outcomes of our studies align with and substantiate certain evidence in the literature documenting bone resorption, specifically at the level of the implant neck and near the cortical bone. The study aims to provide a comprehensive understanding of angled abutment stress patterns in the bone surrounding dental implants, offering valuable insights for clinical applications in critical areas of the mouth.

Stiffness-driven design and optimization of a 3D-printed composite prosthetic foot: A beam finite Element-Based framework

Composite foot prostheses are traditionally produced via lamination, a process that grants high structural efficiency. However, it is an expensive and time-consuming process. Production rate and customizability are thus limited. Additive manufacturing of composites can be a potential solution to these limitations. This work presents a tool to design and optimize Continuous Fiber-Reinforced Additively Manufactured (CFRAM) prosthetic feet using beam Finite Element (FE) modeling. This optimization tool was developed for weight minimization and obtaining a CFRAM prosthesis design matching up to three static stiffness parameters. The design variables were defined through parametrizing the geometry of the prosthesis designed and using the composite structure parameters. Thanks to the versatility of the tool, solutions to multiple optimization and design cases were used to assess different design concepts, such as the shape of the prosthesis (C-shape or J-shape). Also, the tool successfully duplicated the stiffness characteristics of an assumed laminated prosthesis. Finally, the sources of inaccuracy associated with the beam FE modeling approach were identified through a comparison with plane stress FE analysis.

Theoretical and Finite Element Analysis of Pressure Vessel

Objectives: This study tests the vessel strength and performance of pressure vessel under Internal pressure, Nozzle loads, and Hydro-test using Ansys APDL, validating design alignment with ASME Section VIII following the Design by rule (Analytical) and Design by Analysis (FEA) accurate elastic analysis approach. Methods: This study employs ASME methods to validate vessel integrity under various loads. Strength is confirmed through analytical formulas and Finite Element Analysis (FEA) using ANSYS APDL, aligned with widely used ASME BPVC codes in the oil and gas industry. The FE model, utilizing hex elements, ensures result accuracy with a minimum of three elements across thickness. Boundary conditions are validated by comparing hoop stress in FEA with analytically calculated values. ASME's computationally efficient elastic analysis, employing a linear approach, includes stress linearization at discontinuity and non-discontinuity locations, verifying vessel design through analysis. Findings: Initial thicknesses for the shell and cone exceeded analytically calculated minimums, affirming vessel structural integrity through ASME's design by rule approach. Finite Element Analysis (FEA) stress analysis at critical points, such as nozzle junctions and other discontinuity areas, validates accuracy through hoop stress checks. Analysis of design and test load cases reveals stress categories well within ASME Sec VIII limits, confirming the vessel's safety and compliance with elastic stress analysis standards. Novelty: This method emerges as a reliable tool for vessel design, ensuring safety and ASME compliance, particularly beneficial for industries like oil and gas. It provides precise guidelines utilizing hex mesh, validates boundary conditions through hoop stress comparison, and comprehensively assesses stress in critical and non-critical zones through elastic stress analysis. Addressing common challenges identified in the literature review, this approach enhances the accuracy and reliability of pressure vessel designs in compliance with ASME standards for design and test loadings. Keywords: Pressure Vessels, Process Industries, Stress, Loads, Pressure, Thermal, Design Validation, ASME, FE analysis

Design and Research on the Mechanical Structure of a Heavy-Duty Hexapod Robot with Bouncing Characteristics

Based on the lunar exploration project, a mechanical structure design scheme for a heavy-duty hexapod robot movement system with bounce characteristics was proposed. The materials used were determined by the robot's working environment and performance standards. The mechanical structure of a jumping heavy-duty hexapod robot was designed using SolidWorks 3D modeling software. Based on the analysis of the working modes of the root joint, hip joint, knee joint, and jumping energy storage mechanism, the main components of each joint and jumping energy storage mechanism were designed, and a single leg mechanism was obtained. Based on the special soil structure on the lunar surface, the foot end buffer mechanism was designed, and finite element stress analysis was conducted on the key components of the robot model, proving the rationality of the mechanical structure of a heavy-duty hexapod robot with bounce characteristics.

Mathematical Modeling and Finite Element Analysis of Residual Stress (RS) Field after Multipass Ultrasonic Surface Rolling

In order to achieve the change rule of the induced residual stress (RS) field after multipass ultrasonic surface rolling (USR), a mathematical model of the induced residual stress (RS) field after multipass ultrasonic surface rolling is first established. Then, the coupling mechanisms of the RS field after dual-pass USR and multipass USR are analyzed, respectively. Subsequently, a finite element (FE) model is established, and the influence of the interval between two adjacent rolling paths LS is investigated. Finally, both the mathematical model and the FE model are experimentally verified. The results show that both the mathematical model and the FE model can predict the RS field after multipass USR. Two adjacent RS fields will couple with each other in their overlapping regions. For a relatively small interval LS, the RS field after multipass USR can be fully coupled, so as to form a uniform compressive RS layer. In this study, when LS = 0.05 mm, the values of the surface compressive RS, the maximum compressive RS, the depth of the maximum compressive RS, and the depth of the compressive RS layer reach 426.71 MPa, 676.54 MPa, 0.05 mm, and 0.54 mm, respectively.

Structural strength analysis of a rotary drum mower during harvesting

A Rotary Drum Mower (RDM) is a tractor-mounted mechanism used for harvesting green fodder crops. It faces dynamic forces from rough field surfaces and cutting resistance, posing design challenges and potential failures. This study aims to present a well-designed procedure for analysing the structural strength of an RDM during harvesting, employing both experimental and engineering simulation methods. A specific harvesting scenario was created to simulate realistic load conditions. Experimental testing and advanced computer-aided engineering (CAE) simulations were conducted. Tractor Power Take-off (PTO) torque measurements during harvesting revealed values of 231.07 Nm, 264.44 Nm, and 269.39 Nm at speeds of 8.56 km h-1, 12.6 km h-1, and 16.23 km h-1, respectively. Finite element analysis (FEA) was conducted to determine stress levels in the RDM components (RDM165-A-004, RDM165-B-003, and RDM165-B-004). The FEA stress results ranged from 5.070 MPa to 20.600 MPa, 13.800 MPa to 28.600 MPa, and 5.400 MPa to 27.550 MPa, respectively. Experimental testing yielded stress results ranging from 2.127 MPa to 18.600 MPa, 14.618 MPa to 33.229 MPa, and 8.838 MPa to 31.248 MPa, respectively. The comparison between experimental and FEA results showed reasonable correlation. FEA visual outputs provided insights into the maximum equivalent stress and deformation distributions on the RDM, with no indications of failure in the machine's structure observed in either the experimental or numerical analyses. In conclusion, this study demonstrates that the machine analysed operates safely under harvesting conditions. Moreover, the combination of experimental and advanced CAE methodologies presented in this research offers a valuable approach for future investigations into the complex stress and deformation evaluations of rotary drum mowers.

FEA-Based Stress-Strain Barometers as Forecasters for Corneal Refractive Power Change in Orthokeratology.

To improve the effectivity of patient-specific finite element analysis (FEA) to predict refractive power change (RPC) in rigid Ortho-K contact lens fitting. Novel eyelid boundary detection is introduced to the FEA model to better model the effects of the lid on lens performance, and stress and strain outcomes are investigated to identify the most effective FEA components to use in modelling. The current study utilises fully anonymised records of 249 eyes, 132 right eyes, and 117 left eyes from subjects aged 14.1 ± 4.0 years on average (range 9 to 38 years), which were selected for secondary analysis processing. A set of custom-built MATLAB codes was built to automate the process from reading Medmont E300 height and distance files to processing and displaying FEA stress and strain outcomes. Measurements from before and after contact lens wear were handled to obtain the corneal surface change in shape and power. Tangential refractive power maps were constructed from which changes in refractive power pre- and post-Ortho-K wear were determined as the refractive power change (RPC). A total of 249 patient-specific FEA with innovative eyelid boundary detection and 3D construction analyses were automatically built and run for every anterior eye and lens combination while the lens was located in its clinically detected position. Maps of four stress components: contact pressure, Mises stress, pressure, and maximum principal stress were created in addition to maximum principal logarithmic strain maps. Stress and strain components were compared to the clinical RPC maps using the two-dimensional (2D) normalised cross-correlation and structural similarity (SSIM) index measure. On the one hand, the maximum principal logarithmic strain recorded the highest moderate 2D cross-correlation area of 8.6 ± 10.3%, and contact pressure recorded the lowest area of 6.6 ± 9%. Mises stress recorded the second highest moderate 2D cross-correlation area with 8.3 ± 10.4%. On the other hand, when the SSIM index was used to compare the areas that were most similar to the clinical RPC, maximum principal stress was the most similar, with an average strong similarity percentage area of 26.5 ± 3.3%, and contact pressure was the least strong similarity area of 10.3 ± 7.3%. Regarding the moderate similarity areas, all components were recorded at around 34.4% similarity area except the contact pressure, which was down to 32.7 ± 5.8%. FEA is an increasingly effective tool in being able to predict the refractive outcome of Ortho-K treatment. Its accuracy depends on identifying which clinical and modelling metrics contribute to the most accurate prediction of RPC with minimal ocular complications. In terms of clinical metrics, age, Intra-ocular pressure (IOP), central corneal thickness (CCT), surface topography, lens decentration and the 3D eyelid effect are all important for effective modelling. In terms of FEA components, maximum principal stress was found to be the best FEA barometer that can be used to predict the performance of Ortho-K lenses. In contrast, contact pressure provided the worst stress performance. In terms of strain, the maximum principal logarithmic strain was an effective strain barometer.

Effect of a 10-Methacryloyloxydecyl Dihydrogen Phosphate- treated Bioceramic Sealer on the Bond Strength of an Endodontic Fiber Post: Multilayer Composite Disk Models and Ultra-highspeed Imaging Analysis

Multiple materials are found in the root canal after fiber-post cementation. The layer of a bioceramic-based (BC) sealer may affect the bond strength (σBS) of the fiber post in the root canal. The purpose of this study was to employ multilayer compos-ite-disk models in diametral compression to investigate whether the bond strength between a fiber post and root dentin can be in-creased by the application of a primer on the BC sealer. The multilayers of materials in the root canal required 3D finite-element (FE) stress analyses (FEA) to pro-vide precise σBS values. First, BC sealer was characterized using x-ray powder diffraction (XRD) to determine when the sealer com-pletely set and the types of crystals formed to select which primer to apply to the sealer. We selected a 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP)-based primer to treat the BC sealer before post cementation. Ultra-highspeed (UHS) imaging was utilized to analyze the crack initiation interface. The obtained failure force was used in FE analysis to calculate σBS. UHS imaging validated the fracture interface at the post-dentin junction as FEA simulations predicted. σBS values of the fiber posts placed with various material combinations in the root canal were 21.1 ± 3.4 (only cement/ post), 22.2 ± 3.4 (BC sealer/cement/post) and 28.6 ± 4.3 MPa (10-MDP primer treated BC sealer/cement/post). The 10-MDP-treated BC sealer exhibited the highest σBS (p < 0.05). The multilayer composite disk model proved reliable with diametral compression testing. The presence of BC sealer in the root canal does not reduce σBS of the fiber post. Conditioning the BC sealer layer with 10-MDP primer before fiber-post cemen-tation increases σBS.

Evaluation of Zirconia Paediatric Crowns and Stainless-steel Crowns using Finite Element Stress Analysis

Introduction: The aim of this study is to perform Finite Element Stress Analysis (FEA) to determine the stress that stainless-steel and zirconium materials apply to the primary teeth while under occlusal and lateral forces, in order to predict possible situations that may occur in restorative materials and dental tissues as a result of their clinical use. Objective: The study groups were as follows: stainless-steel crown cemented by glass ionomer cementand dual cure resin cement; zirconium paediatric crown cemented by glass ionomer cement and dual cure resin cement. The control group was the tooth model without decay.

Assessment of Stress Distribution with 3 Taper Design Preparation of Root Canal Using Finite Element Analysis.

Present research was done to assess stress distribution in three different taper design preparation of root canal with the help of finite element analysis. Lower incisors teeth having single canals that were cleaned and shaped with the help of NeoEndo Flex Titanium (NiTi) rotary file and later three designs were created such as 4%, 6%, and 8% canal preparation taper. Cone beam computed tomography (CBCT) was done for all teeth and subjected to finite element analysis for stresses. The collected data were statistically analyzed. Highest stress was found in the coronal followed by the middle and least in the apical part in all three designs. The highest stress value was found in enamel than dentin (MPa). The highest stress value was found with design 3 (8% taper) followed by designs 2 (6% taper) and 1 (4% taper) for enamel and dentin with either oblique or vertical stress loading. All canals preparation exhibited maximum enamel stress at the coronal load points compared to apical and middle portions. The stress increases with increase in canal tapering.

Multicrystalline Informatics Applied to Multicrystalline Silicon for Unraveling the Microscopic Root Cause of Dislocation Generation.

A comprehensive analysis of optical and photoluminescence images obtained from practical multicrystalline silicon wafers is conducted, utilizing various machine learning models for dislocation cluster region extraction, grain segmentation, and crystal orientation prediction. As a result, a realistic 3D model that includes the generation point of dislocation clusters is built. Finite element stress analysis on the 3D model coupled with crystal growth simulation reveals inhomogeneous and complex stress distribution and that dislocation clusters are frequently formed along the slip plane with the highest shear stress among twelve equivalents, concentrated along bending grain boundaries (GBs). Multiscale analysis of the extracted GBs near the generation point of dislocation clusters combined with ab initio calculations has shown that the dislocation generation due to the concentration of shear stress is caused by the nanofacet formation associated with GB bending. This mechanism cannot be captured by the Haasen-Alexander-Sumino model. Thus, this research method reveals the existence of a dislocation generation mechanism unique to the multicrystalline structure. Multicrystalline informatics linking experimental, theoretical, computational, and data science on multicrystalline materials at multiple scales is expected to contribute to the advancement of materials science by unraveling complex phenomena in various multicrystalline materials.

Back-analyses of soft soil failure with "strain-softening" behavior by the "equivalent sensitivity" concept

Stability analyses of slopes in soft soils are usually affected by strain-softening, resulting in unrealistic (unconservative) safety factors. The loss of post peak strength cannot be accounted for by classic limit equilibrium analyses. In practice, however, the overall loss of soil strength is generally approximated by Bjerrum correction factor μ ≤ 1, which is believed to account for the different failure velocities during the field tests (usually vane tests) and the actual failure in the field, in addition to anisotropy (Schnaid &amp; Odebrecht, 2012). The objective of this work is to demonstrate that strain-softening reduces the overall safety factor to a value nearly equivalent to the application of Bjerrum’s correction factor. To accomplish this, a simple constitutive model (Mohr-Coulomb with residual stress) is used for total stress finite element analyses by means of the concept of “equivalent sensitivity” proposed by Pereira Pinto (2017). The results showed that equivalent sensitivity can be a great instrument to simulate the strain-softening behavior of soft soils.

A Poisson–Voronoi-based finite element stress analysis of resonating polysilicon micromachines

A Poisson–Voronoi-based finite element stress analysis of resonating polysilicon micromachines