Von Mises Failure Criterion Research Articles

Trabecular Bone Component Assessment under Orthodontic Loads and Movements during Periodontal Breakdown-A Finite Elements Analysis.

This numerical analysis, by employing Tresca and Von Mises failure criteria, assessed the biomechanical behavior of a trabecular bone component subjected to 0.6, 1.2, and 2.4 N orthodontic forces under five movements (intrusion, extrusion, tipping, rotation, and translation) and during a gradual horizontal periodontal breakdown (0-8 mm). Additionally, they assessed the changes produced by bone loss, and the ischemic and resorptive risks. The analysis employed eighty-one models of nine patients in 405 simulations. Both failure criteria showed similar qualitative results, with Tresca being quantitatively higher by 1.09-1.21. No qualitative differences were seen between the three orthodontic loads. Quantitatively, a doubling (1.2 N) and quadrupling (2.4 N) were visible when compared to 0.6 N. Rotation and translation followed by tipping are the most stressful, especially for a reduced periodontium, prone to higher ischemic and resorptive risks. In an intact periodontium, 1.2 N can be safely applied but only in a reduced periodontium for extrusion and intrusion. More than 0.6 N is prone to increasing ischemic and resorptive risks for the other three movements. In an intact periodontium, stress spreads in the entire trabecular structure. In a reduced periodontium, stress concentrates (after a 4 mm loss-marker for the stress change distribution) and increases around the cervical third of the remaining alveolar socket.

Failure strength of glacier ice inferred from Greenland crevasses

Abstract. Ice fractures when subject to stress that exceeds the material failure strength. Previous studies have found that a von Mises failure criterion, which places a bound on the second invariant of the deviatoric stress tensor, is consistent with empirical data. Other studies have suggested that a scaling effect exists, such that larger sample specimens have a substantially lower failure strength, implying that estimating material strength from laboratory-scale experiments may be insufficient for glacier-scale modeling. In this paper, we analyze the stress conditions in crevasse onset regions to better understand the failure criterion and strength relevant for large-scale modeling. The local deviatoric stress is inferred using surface velocities and reanalysis temperatures, and crevasse onset regions are extracted from a remotely sensed crevasse density map. We project the stress state onto the failure plane spanned by Haigh–Westergaard coordinates, showing how failure depends on mode of stress. We find that existing crevasse data are consistent with a Schmidt–Ishlinsky failure criterion that places a bound on the absolute value of the maximal principal deviatoric stress, estimated to be 158±44 kPa. Although the traditional von Mises failure criterion also provides an adequate fit to the data with a von Mises strength of 265±73 kPa, it depends only on stress magnitude and is indifferent to the specific stress state, unlike Schmidt–Ishlinsky failure which has a larger shear failure strength compared to tensile strength. Implications for large-scale ice flow and fracture modeling are discussed.

Material Behavior of PIR Rigid Foam in Sandwich Panels: Studies beyond Construction Industry Standard.

A deep understanding of the material parameters and the behavior of sandwich panels, which are used in the construction industry as roof and façade cladding, is important for the design of these construction components. Due to the constant changes in the polyurethane (PU) foams used as a core material, the experimental database for the current foams is small. Nowadays, there is an increasing number of failures of façade and roof panels after installation. This article presents a variety of experimental investigations on sandwich panels from two manufacturers with a core of polyisocyanurate (PIR) rigid foam (density: 40 kg/m3). As part of this study, compression, tension, shear, and bending tests were performed in several spatial directions and over the range required by the standard. The results of the tests showed the orthotropy of the core material and the dependence of the material on the direction and type of load. The stress-strain curves showed linear and non-linear areas. Using the data from this experimental study, a numerical model was implemented which utilized the Hill yield criterion to represent the orthotropy of the core material. The present investigation suggests that the classical von Mises failure criterion, used in many studies, is not suitable for the foam system applied in these sandwich panels. Instead, the Tsai-Wu criterion is more appropriate for defining the failure stresses.

Behavior of Composite Parts Adhesively Joined With Single Lap Joint and Intermediated Material Under Tensile Load

In research, composite parts adhesively joined with single-lap joint (SLJ) and intermediated material under tensile load were examined by finite element analysis (FEA). While T700 Carbon/epoxy was used for composite parts and intermediate material, DP 410 type was preferred for adhesive. The numerical studies were carried out by ANSYS 14.5 based on finite elements method. The von-Mises failure criteria and the Tsai-wu failure criteria were respectively considered for adhesive and composites. The analyses were firstly actualized to determine the failure loads for each parameter situation. The stresses at obtained failure load for each parameter state were investigated. The critical equivalent stresses on adhesive layers were examined and the critical stress lines for length and width was determined. The distributions of normal and shear stresses in all directions were obtained by considering critical stress line on adhesive layers. Similarly, the von-Mises stress distributions were obtained. Considering critical stress lines, the stress distributions on width and length of overlap dimensional were compared. The effects of overlap dimensional, orientation angle and intermediated material on effect of joint zone were investigated.

Mechanical analysis of composite plates adhesively joined with different single-lap techniques under bending loading

Abstract In this study, composite plates adhesively joined using single-lap joint without intermediated material (SLJ) and intermediated material (IM-SLJ) subject to bending loading were investigated via finite element analysis. DP 410 type adhesive was used. Composite parts and intermediate material were preferred as T700 carbon/epoxy. Numerical analyses were carried out using ANSYS 14.5 software package, in which the finite element method was taken into account. Failure situations for adhesive and composites were examined by the von-Mises failure criteria and the Tsai-wu failure criteria, respectively. Firstly, the failure loads for each parameter situation were determined. The equivalent stresses of the critical stress lines on adhesive layers were examined and critical stresses line were determined for length and width of adhesive layers. Shear, normal, and von-Mises stresses were investigated at obtained failure load for each parameter of SLJ and IM-SLJ. The von-Mises on the critical stress lines were compared for different overlap width and length of SLJ and IM-SLJ. The effects of joint techniques, orientation angles, and overlap dimensional were investigated on adhesive layer, and joint techniques were compared about advantages. A different study from the literature was carried out to compare the mechanical behavior of SLJ and IM-SLJ joining techniques.

A trishear model with self-adaptive propagation-to-slip ratio

Natural beds at different stratigraphic levels display different degrees of folding. Variable propagation-to-slip ratios in the trishear models are more appropriate for the reproduction of natural folds. An improved trishear model with self-adaptive propagation-to-slip ratio, called TMSP, is proposed in this paper. Transverse isotropy elastic constitutive relationships are utilized to formulate the mechanic behaviors of the overlying sediments. The von Mises failure criterion is introduced to determine whether the material points are destroyed in TMSP. Compared with previous trishear models, TMSP has the advantage that propagation-to-slip ratio can be updated with the proceeding of fault rupture propagation and is not required to be predetermined. A natural fault-propagation fold, Tejerina fold, can be reproduced well by TMSP. Finally, a series of simulations are conducted to investigate the influences of three key parameters of TMSP, including apical angle, yield stress, and elastic modulus, on faulting process and folding growth.

Comparison of stress distribution between zirconia/alloy endocrown and CAD/CAM multi-piece zirconia post-crown: three-dimensional finite element analysis.

This study aimed to evaluate a digital multi-piece zirconia post-crown to restore a mandibular second molar with extensive coronal loss and limited restoration space, and to compare the stress distribution between endocrowns made of zirconia or alloy and CAD/CAM multi-piece zirconia post-crowns. Four three-dimensional finite element analysis models of a mandibular second molar with extensive coronal loss and limited restoration space were created as follows: (A) intact molar; (B) zirconia endocrown restored molar; (C) multi-piece post-crown restored-molar with tapered nail; (D) multi-piece post-crown restored molar with T-shaped nail. Models C and D were divided into two subgroups according to the material type: C1/D1, zirconia; C2/D2, NiCr alloy. The maximum modified von Mises failure criterion (mvM) stresses were calculated, and the stress distribution was recorded to analyze the effects of the restoration and material types on the biomechanical properties of dentin and prosthesis. The maximum mvM stress of dentin in model B (33.80MPa) was lower compared with models C (C1, 37.81MPa; C2, 36.36MPa) and D (D1, 36.34MPa; D2, 34.97MPa) under vertical load, but the opposite was observed under oblique load. The highest mvM stress was concentrated in the nail region located in the root canal, and the T-shaped nail values were greater than the tapered nail, whereas model D with T-shaped nail showed a lower mvM stress level in dentin compared with Model C with tapered nail. The digital multi-piece zirconia post-crown is a potential approach to restore mandibular second molars with extensive coronal loss and limited restoration space. The digital multi-piece zirconia post-crown has potential to restore mandibular second molars with extensive coronal loss and limited restoration space using an innovative approach.

Influence of fiber insertion and different material type on stress distribution in endocrown restorations: a 3D-FEA study

The study aimed to evaluate the effects of fibers insertion and restorative material type on the stress distribution in endocrowns with finite element analysis. Five 3D models of first mandibular molars were created and restored as follows: (1) IN: intact tooth, (2) IPS-E: tooth restored with lithium disilicat ceramic endocrowns, (3) C-E: tooth restored with composite endocrowns, (4) IPS-E + F: lithium disilicate ceramic endocrowns + fiber, (5) C-E + F: composite endocrowns + fiber. Vertical masticatory load was imitated with finite element analysis. The equivalent stress of von Mises failure criterion (mvM) was calculated. The maximum mvM stress, enamel/crown, dentin and cement were compared among models and strength of the materials. Endocrowns presented a lower mvM stress level than intact tooth. In IPS-E, the mvM stress values in the crown and dentin were higher than C-E, while the mvM stress values in cement were higher in C-E group. Fibers insertion did not affect the stress level of IPS-E and C-E groups. In IPS model, fiber showed more stress absorption than C-E. The restorative material type changed the stress distribution of endocrown restorations. The fiber application did not affect the stress distribution in either endocrown group. But, more stress absorption was observed in fiber under IPS-E than C-E.

Tensile properties of defect-prefabricated 3D woven composites: Experiments and simulations

Three-dimensional (3D) woven composites have been widely used in structural components due to their excellent mechanical and near-net-shape properties. However, for some special applications, it is expected that 3D woven composites can be damaged at designated locations under a specific load. In this research work, a new kind of defect-prefabricated 3D woven composites (DP3DWCs) are designed, where defects are prefabricated by cutting weft or warp yarns in defect-free 3D woven composites (DF3DWCs). The tensile mechanical properties of the DF3DWCs and the DP3DWCs are investigated experimentally and numerically. The mesoscopic geometry models of the DF3DWCs and the DP3DWCs were established by multi-objective searching algorithm. The progressive damage models were established using the 3D Hashin criteria and the von Mises failure criterion. Numerical results agree well with the experimental data. The influence of the number of defect layers on the mechanical properties was also discussed. The obtained results indicate that the defects have little effect on the elastic modulus, while tensile strengths decrease linearly with the increase of the number of defect layers. Failure mechanisms of yarns and matrix in the non-defective and defective materials were studied, and the volume fraction of elements of each failure mode was computed and analysed.

Investigation of the thermoelastoplastic behaviors of multilayer FGM cylinders

A finite difference numerical solution for the thermoelastoplastic performance of rotating multilayer (sandwich) cylinders is presented while considering the materials' properties temperature dependency. Each layer is treated as a composite with volume fractions being constant, independent on the position, and unique. The cylinder is rotating with a variable (exponential) angular speed leading to the presence of shear stress. Regarding plasticity analysis, von Mises failure criterion is considered while the constituent materials have a nonlinear strain hardening. Different case studies are examined and discussed. Results revealed that the layers' arrangement and the maximum temperature position substantially influence the cylinder's performance. Additionally, cylinders with smaller size are able to sustain the prescribed loads compared to larger ones.

Numerical Analysis of the ACL, with Sprains of Different Degrees after Trauma.

Nowadays, cruciate ligament injuries have increased in incidence, since practicing a sport or physical activity has become a trend in current societies. Although this lifestyle generates multiple benefits, as a consequence, injury has also increased. Due to its nature and complexity, the ligaments of the knee are those that are most frequently affected, mainly the ACL (anterior cruciate ligament). This tissue reacts to overexertion or movements out of range, either caused by the exercise itself or caused by trauma caused by the practice of physical activity, causing various degrees of sprain. Whatever the etiology of these injuries, they will require a therapy indicated for each degree of injury. This therapy initially entails immobilization of the affected area and later; physical therapy will be required to a lesser or greater degree. Commonly, in the physiotherapy of these injuries, rehabilitation exercises are prescribed, where the physiotherapist asks a patient to use equipment with an estimated weight. However, the effectiveness of a generalized therapy in this way does not always give the expected results. This is related to the fact that these therapies are standardized and do not consider some factors such as the remaining muscle fibres that are not directly affected by the sprain, which does not mean that they should not be considered. Therefore, in the present work, a biomodel of a human knee has been developed and used to evaluate numerically how the ACL acts under an external load, when there are different degrees of injuries, caused by trauma. Four case studies were considered: Case 1 (control case) where the ACL is healthy, Case 2 where the ACL presents a 1st-degree sprain, Case 3 where the ACL presents a 2nd-degree sprain, and finally Case 4 where the ACL presents a 3rd-sprain grade. After performing the analyses, in the control case, it was found that it presents a balance between tensile and compressive stresses. While in the 4th case, the most critical tensile stress decreases while compression stresses increase. This shows that the ligament, having considerable damage, no longer works as it should and can eventually damage the collateral structures. It was found that, when there was a sprain, where the continuity of the ligament is compromised, a second torsional moment occurs in the ACL which causes the tissue fibres not to act according to their normal physiology or in a healthy state. The results obtained from the present study provide the possibility of predicting where the following injuries will occur by considering the von Mises failure criterion. Likewise, they will allow to improve the therapeutic procedures considering not only the injured structure but also the system as a whole.

Evaluation of stress in three different fiber posts with two-dimensional finite element analysis.

The primary function of corono-radicular post is to provide retention for the core and to reinforce and to replace the remaining coronal tooth structure. There is considerable controversy regarding optimal choice of the material. An ideal post system should exhibit fracture resistance higher than the average masticatory forces. Finite elemental analysis (FEA) method facilitates precise analysis of the distribution and magnitude of stresses at any point of complex and irregular structures. Thus, this FEA study has been undertaken to evaluate the fracture stress distribution patterns in three fiber posts, viz., carbon, glass fiber, and everStick with an FEA. The FE stress analysis was performed with the FE software program (CATIA). Three two-dimensional FEA models of central incisor were simulated, and elastic moduli and Poisson's ratio of all the materials were fed to the software. For all the models, a 200 N vertical force was applied on the lingual surface of the tooth at an angle of 45°. Stress concentration and distribution were evaluated and noted down for all the models. To evaluate the stresses within the restored tooth, the modified von Mises failure criterion was used. The equivalent stresses found in the tested models were compared with the tensile strength of the respective materials. Contact stresses in the luting cement-dentin interface were calculated. Finite element method revealed that maximum stress concentration was at the point of stress application. The stress value was highest in carbon fiber post followed by glass fiber post and least stresses found in everStick post. Maximum stress was observed at the labial surfaces of crown. However, the stress values and distribution were more homogenous in everStick post. The present findings suggest that everStick post has uniform stress distribution within tooth structure.

Analysis of Undrained Seismic Behavior of Shallow Tunnels in Soft Clay Using Nonlinear Kinematic Hardening Model

In this study, a soil–tunnel model for clay under earthquake loading is analyzed, using finite element methods and a kinematic hardening model with the Von Mises failure criterion. The results are compared with those from the linear elastic–perfectly plastic Mohr–Coulomb model. The latter model does not consider the stiffness degradation caused by imposing cyclic loading and unloading to the soil, whereas the kinematic hardening model can simulate this stiffness degradation. The parameters of the kinematic hardening model are calibrated based on the results of experimental cyclic tests and finite element simulation. Here, two methods—one using data from cyclic shear tests, and the other a new method using undrained cyclic triaxial tests—are used to calibrate the parameters. The parameters investigated are the peak ground acceleration (PGA), tunnel lining thickness, tunnel shape, and tunnel embedment depth, all of which have an effect on the resistance of the shallow tunnel to the stresses and deformations caused by the surrounding clay soils. The results show that unlike traditional models, the nonlinear kinematic hardening model can predict the response reasonably well, and it is able to create the hysteresis loops and consider the soil stiffness degradation under the seismic loads.

Limit analysis for partial-joint-penetration weld T-joints with arbitrary loading angles

In the present study, limit analysis is performed for T-joints with partial-joint-penetration (PJP) weld by taking advantage of the slip-line field theory and von Mises failure criterion. The strength evaluation equations are derived from the limit analysis and applied to evaluate the ultimate strength of T-joints. The results indicate that ultimate strengths of the longitudinal T-joints are in proportion to the weld throat thickness and independent of weld type. Whereas, the transverse fillet weld and PJP weld T-joints respectively show about 40% and 180% strength increase comparing with their longitudinal counterparts. In addition, the loading angle and material stress ratio effects on the ultimate strength of T-joint are observed depending on the weld types significantly. The finite element models that have been calibrated using the test results are applied to validate analytical results. Good agreements are achieved between the analytical and numerical results regarding the ultimate strengths and fracture angles, which reveals the feasibility and the capacity of the proposed strength equations in evaluating the mechanical behavior of T-joints with arbitrary weld geometries, loading angles, and material stress ratios.

Strength prediction of woven composite rings using progressive damage modeling

The ultimate failure of the woven composite pipes has been investigated using progressive damage modeling. The composite pipe specimens were made of (E) glass plain weave fabrics according to the ASTM D2290 standard. The hoop strength of these specimens has been obtained from the tensile tests. The damage initiation and propagation of composite pipe have been predicted by a numerical multi-scale method. For this purpose, the damage of the yarns and resin of the plain weave laminate was investigated by modeling a representative volume element. Then, the macroscopic stresses and strains of the representative volume element were calculated to obtain the equivalent stiffness matrix using suitable boundary conditions. Then, the mechanical properties of the laminate and material properties degradation coefficients were derived by this equivalent stiffness matrix. Hashin and Von Mises failure criteria were utilized in USDLFD subroutine to predict the damage initiation of the yarn and resin in the representative volume element, respectively. The sudden degradation method has been used to investigate the damage propagation in these constituents. Then, the woven composite ring was modeled in ABAQUS software and its ultimate strength was predicted by UMAT subroutine using obtained degradation coefficients of the representative volume element from the previous step. Finally, the numerical results were compared with the experimental data which show good agreement between the results.

Investigation of Seismic Behavior of Clay‐Pile Using Nonlinear Kinematic Hardening Model

In geotechnical mediums where the bearing capacity of upper layers of soil is not suitable for use of the shallow foundations, piles are usually used as deep foundations to transfer loads to the stronger lower layers. Here, the seismic behavior of single pile and pile group constructed in saturated soft kaolin clay under three different earthquakes using Abacus 3D software is investigated. The aluminum material considering the linear elastic model has been used for the piles, and the nonlinear kinematic hardening model with Von Mises failure criterion has been considered for clay. This model can consider the soil stiffness degradation by increasing the number of cyclic loading. Three different methods have been used to calibrate the model parameters, two of them are new methods. In all calibration methods, the cyclic shear and undrained cyclic triaxial tests are used. The results obtained from the numerical analysis of the soil‐pile model are in relatively good agreement with the centrifuge model results. According to the results, the variation of earthquake frequency and intensity affects the bending moment created along the pile and also the distance between piles in a pile group affects the amount of the interaction between them.

Numerical analysis of damage zones in a bridge

PurposeThe purpose of this paper is to present a numerical analysis of structural monitoring for damage zones detection. The study is performed with Ansys finite element software, which reads in batch mode programming a previously generated mesh data file and computes the transient dynamic solution for each time-step iteration within an analysis time range.Design/methodology/approachThe approach itself is applied on a bridge structure which can be potentially subjected to damage zones due to severe loads cases and or earthquakes vibrations. The ideal Von Mises failure criterion ellipsoid envelope is applied for the detection of overstepped computed stresses and strains.FindingsThis numerical analysis allows computing, for each time-step iteration, the dynamic displacements at each degree of freedom and the corresponding stresses and strains inside the elements under the action of several times dependent loads cases.Practical implicationsSeveral simulations are considered to quantify the external loads.Originality/valueThe material properties of reinforced concrete RC are calculated for an existing specific bridge structure case. The RC strength is then introduced from the basic compounds material properties using the corresponding volumes fractions.

Strength and failure characteristics of a glass fiber SMC-R composite under combined tensile and shear stresses

Sheet molding compounds with randomly oriented short fibers (SMC-R) is considered a suitable lightweight alternative for steel and aluminum alloys in many structural automotive components. It is also finding a few applications in the aircraft industry. This study focuses on the quasi-static behavior of a glass fiber SMC-R composite under biaxial loading with a combination of tensile and shear stress components. A butterfly shaped Arcan specimen was used to generate the biaxial loading conditions. It was observed that the failure load is lower under combined tensile and shear loading conditions compared to uniaxial loading conditions. Damage development in SMC-R causes the material to change from a linear behavior to a non-linear behavior at the knee load. The degree of non-linearity increases with increasing shear stress. The failure envelopes based on the nominal principal stresses in the significant section of the Arcan specimen show that von Mises failure criterion used for isotropic materials gives a reasonable agreement with the experimental data.

Burst pressure assessment of corroded pipelines using fracture mechanics criterion

In the conventional method of analysis for the remaining strength assessment of a corroded pipeline, von Mises failure criterion is used. This continuum-based modelling approach is unable to assess the cracking of the pipeline. In this study, a fracture mechanics approach is used for the assessments of burst pressures of pipelines with corrosion only defects, pipelines with crack-like defects and pipelines with crack-in-corrosion defects. The fracture mechanics approach with the J-integral was found to simulate successfully the burst pressures obtained from rapture tests of pipelines with corrosion only defects and crack-in-corrosion defects. The conventional von Mises stress-based approach and design equations can reasonably be used for predicting the burst pressures of pipelines with corrosion only defects. However, the fracture mechanics approach is required for pipelines with crack-like defects and crack-in-corrosion defects. A parametric study is presented with calculations of the J-integrals for pipelines with crack-in-corrosion defects for various crack depths and crack lengths.

Effects of local stiffness on the spot joints mechanical properties: Comparative study between resistance spot welding and resistance spot clinching joints

Different types of aluminum alloy 5052 (AA5052) resistance spot clinching joints with different local stiffness values were designed in this study. The values of the polar moment of inertia in the cross-section of the fusion zones were calculated. Digital image correlation (DIC) technique was used to study the local rotation and in-plane strain distribution during the lap-shear test of half-cut samples. The results show that the joint with higher local stiffness (polar moment of inertia) value experiences the lowest joining zone rotation during the lap-shear test. This leads to higher proportion of normal component of strain/stress at the periphery of the joining zone. According to Tresca or von Mises failure criterion, for a spot joint, high proportion of normal stress at the load-bearing site enables the global joint to sustain high peak load during tensile test. This mechanism indicates that, compared with conventional resistance spot welding process, the resistance spot clinching technique can improve the mechanical properties of AA5052 joints by increasing the local stiffness.