Von Mises Equivalent Stress Research Articles

Effect of finish line level of all ceramic crown on stress distribution within dentin of maxillary central incisor with an abfraction lesion

Purpose: to evaluate by means of three dimensional finite element analysis, the effect of finish line location on stress distribution on dentin of maxillary central incisor affected by abfraction lesion and covered with IPS e. max (Lithium di silicate) crown. Statement of the problem: In some cases of abfraction, the tooth need to be covered with full coverage crown, but, location of finish line may affect dentin integrity. Materials and Methods: 3D finite element model of unprepared maxillary central incisor was made. By deleting method, IPS e.max crown was designed and geometric dimensions of prepared tooth were introduced as the following guidelines, 2 mm incisal reduction, 1.5 mm reduction of labial surface and 1 mm circumferential shoulder finish line. The position of labial finish line was designed in three different levels apical to the upper margin of the abfraction lesion (0.5. 1.0 and 1.5 mm) forming three models to be tested (A, B and C) respectively in addition to unprepared control model. Results: For all tested four models, the calculated stresses with 125° applied load were higher than that with 60° with statistical significant differences. The calculated stresses at the control model in both directions of applied load were lower than that in other tested models (A, B and C) with statistical significant differences. For control model at 125° applied load, Von Mises equivalent stress value was (40.27 MPa), whereas, in case of 60° applied load, was (26.33 MPa). For model (A) where the finish line of IPS e.max crown is established 0.5 mm apical to the upper edge of the abfraction lesion, Von Mises equivalent stress values were (22.14 & 39.68 MPa) respectively. Conclusion: In all tested models, maximum stresses increased with increasing the angle of applied load, and model (B and C) provided more favorable stress distribution than that in model (A).

Some studies on mathematical modeling and dynamic stress analysis of a variable compression ratio diesel engine crankshaft

The objective of the present work is to investigate the induced stress and deformation of a crank shaft. For this purpose, Variable Compression Ratio (VCR) engine is tested at 16.5 compression ratio. Peak pressures were recorded at various crank angles. A Matlab code is generated for dynamic analysis. For structural analysis and factor of safety, a three dimensional model crank shaft was developed using solid works. Finite element analysis of AISI E4340 Forged steel and Aluminum alloy 7076-T6 materials are carried by using analysis software ANSYS. The obtained results are equivalent Von-Mises stress, total deformation and factor of safety at different crank angles for the two materials are analyzed. It is concluded that Aluminum alloy exhibits better results than forged steel.

Finite element analysis of intramedullary nailing and double locking plate for treating extra-articular proximal tibial fractures

BackgroundProximal tibia fractures are one of the most familiar fractures. Surgical approaches are usually needed for anatomical reduction. However, no single treatment method has been widely established as the standard care. Our present study aims to compare the stress and stability of intramedullary nails (IMN) fixation and double locking plate (DLP) fixation in the treatment of extra-articular proximal tibial fractures.MethodsA three-dimensional (3D) finite element model of the extra-articular proximal tibial fracture, whose 2-cm bone gap began 7 cm from the tibial plateau articular surface, was created fixed by different fixation implants. The axial compressive load on an adult knee during single-limb stance was imitated by an axial force of 2500 N with a distribution of 60% to the medial compartment, while the distal end was fixed effectively. The equivalent von Mises stress and displacement of the model was used as the output measures for analysis.ResultsThe maximal equivalent von Mises stress value of the system in the IMN model was 293.23 MPa, which was higher comparing against that in the DLP fixation model (147.04 MPa). And the mean stress of the model in the IMN model (9.25 MPa) was higher than that of the DLP fixation system in terms of equivalent von Mises stress (EVMS) (P < 0.0001). The maximal value of displacement (sum) in the IMN system was 8.82 mm, which was lower than that in the DLP fixation system (9.48 mm).ConclusionsThis study demonstrated that the stability provided by the locking plate fixation system was superior to the intramedullary nails fixation system and served as an alternative fixation for the extra-articular proximal tibial fractures of young patients.

The modeling and optimization of hot rolling process of A36 structural steel by using response surface methodology

In hot conditions and with various parameters, it has been found several cracks and wear in the hot rolling process due to several factors including von mises stress and plastic strain which is affected by the size of the roller diameter and thickness of the specimen. Modeling and optimization using Response Surface Methodology (RSM) are chosen in this study to determine the optimum parameter design. The effect of roller diameter and thickness of specimens on equivalent stress von mises and plastic strains on the hot rolling process were studied using RSM. Central Composite Design (CCD) with two factors and three levels which are part of the RSM used to present mathematical models. Based on the results of RSM the optimum value obtained is on the roller diameter of 577.1389 mm and the thickness of the specimen 8.5786 mm.

Numerical Simulation of Wheel-rail Interfaces in Heavy Freight Corridors using Hybrid Rigid-deformable Model

Design and operation of dedicated railway freight corridors require detailed analysis of the arduous loading conditions imposed by trains during heavy load transit. A hybrid rigid-deformable numerical model is formulated for estimating the increase in wheel-rail frictional stresses, contact pressures, equivalent von-Mises stresses and strains produced in the axle, corresponding to an increase in the applied axle load. The hybrid model considers the wheel-rail system to be a combination of deformable wheel-set running on rigid rails, which considerably reduces the computational demands and time associated with the analysis of large number of nodes and elements in the numerical model. Validation of the model was done by analyzing a section of Italian rail UNI-60 and contact pressure results were correlated with the data available from literature. Wheel-rail contact analyses were then performed on Indian Railways IRS-52 track section, for heavy axle loads upto 32.5 tonnes, as proposed by Indian Railways for dedicated freight corridors. A Hertzian elliptical contact patch was observed at the wheel-rail interface. Assessment of contact pressure and frictional stresses were then done at the wheel-rail interfaces for a load range of 20 to 32.5 tonnes, and it was noted that the increase in pressures were non-linear, with a quadratic trend. The variation in stresses and strains induced in the axle during loading could also be estimated, since wheel-set was modelled to be deformable in nature. The model analyses are expected to be useful to the railway authorities for designing rail and wheel sections to cater the intense loading conditions in dedicated freight corridors.

Finite Element Analysis of the Efficacy of Shelf Acetabuloplasty for Acetabular Dysplasia

Objective: Shelf acetabuloplasty is a type of joint-preserving surgery. There are only a few cases of studying the mechanical evaluations of shelf acetabuloplasty. The objective of this study was to investigate the biomechanical effects of acetabular dysplasia on the acetabular margin and the efficacy of shelf acetabuloplasty using a threedimensional musculoskeletal model and finite element analysis. Methods: Subjects were five adult female patients with hip osteoarthritis and acetabular dysplasia who underwent the shelf procedure. Using the data of 4 healthy adult women, joint reaction force in the hip joint during static standing was estimated using Any Body Modeling System. From the CT images of each subject, finite element models of the pelvis and the right femur were constructed using Mimics and then converted to a three-dimensional finite element model using 3matic. Stress analysis was carried out using Marc Mentat 2011 1.0 finite element analysis software. In this study, all areas other than soft tissue were considered to be hard bone. In the boundary conditions, the iliac bone and pubic symphysis in the pelvis were fully constrained. Estimated hip joint reaction force was applied as a concentrated load from the distal end of the femur, and von Mises-equivalent stress in the acetabulum was analyzed. The stress distribution, the maximum stress value and the acetabular area applied to the acetabular surface of the acetabulum during resting stance were evaluated before and after the operation. Results: In the stress distribution of the acetabulum during static standing, the stress was dispersed after the operation, and the maximum stress was decreased. The area of acetabular area was significantly increased after the operation. The maximum stress value was significantly decreased after surgery. Conclusion: In all cases, the stress distribution of the acetabulum at the time of standstill standing after the operation of shelf acetabuloplasty was significantly dispersed and decreased as compared with the preoperative state.

Mechanical Behavior of Metal under Hydrostatic Pressure and Low Temperature

The current work describes the behavior of metal under hydrostatic pressure and low temperature using finite element concept. This study was carried out in three stages: modelling, analysis and post processing. Structural steel and aluminum are tested at 600 bar pressure and 4°C temperature. Solid model of cylindrical shape having internal diameter 420 mm and thickness 25 mm was created and same was investigated for stress analysis using ANSYS 17.2 APDL emphasizing on hydrostatic behavior. Failure criterion is based on maximum stress to determine the onset of damage in material. In post processing phase, the material was checked for deformation and equivalent Von-Mises stresses developed around the material. The objective of this present paper is of two fold. Firstly the investigation of metal under high pressure through stress analysis is carried out followed by metallographic studies. The stress analysis results suggest that metals like steel which has BCC structure shows the remarkable decrease in ductility over the range of temperature. The maximum Von Mises stresses that the material can with stand were 65.14 MPa and 56.38 MPa for structural steel and aluminum respectively and revealed having high factor of safety for desired applications. It can be said that aluminum having FCC crystal structure are stiff and ductile even at low subzero temperature. The theoretical calculations are done and they are in agreement with the experimental results. It can be anticipated that influence of high pressure and low temperature can be criticized by two factors in terms of flow strength and fracture strength of metal. Ductile to Brittle Transition Temperature (DBTT) plays a vital role and can be considered as a measure of behavior of metal under high pressure and low temperature. So, it revels that the crystal structures of metals is the major factor which affects the behavior of metal which eventually affect the ductility and toughness of metal when subjected to high pressure and low temperature operations. However, in thick material the question of structural discontinuity and stress concentration is still regarded as open for further scope of study.

Analytical Methods and Finite Element Method Computation The dental - periodontal tissues response

The study of the biomechanical behaviour of dental-periodontal structures during orthodontic movement has been carried out on the basis of the analysis of values of equivalent stress following Von Mises theory, of the stress after the direction of the sz vertical force, which constitutes the essential component of the Von Mises equivalent stress, as well as on the basis of registering the deformities on the tooth axis. The processes of implementation, modelling, calculation and interpretation, using FEM, involved the following steps: defining the geometry and the structure of the model under analysis; meshing the geometry of the structure; connecting the nodal elements; defining the limit conditions and restrictions; loading the created model with vertical forces of different intensities; solving the equation system, having as unknowns in the nodes the following: movement, tension, tension on the spatial coordinates, Von Mises stress. We simulated the orthodontic intrusion through the application of some vertical forces with different intensities and on structures with alveolar bone loss. The tension values in the tooth axis vary in direct proportion to the level of resorption of the alveolar bone, but the decisive element is the numerical value of the applied force, and not the absorption level.

FEA-based structural optimization design of a side cooling collimating mirror at SSRF

Based on finite element analysis of thermal mechanical behavior, structural optimization design was proposed for a side cooling collimating mirror subjected to high heat load for a beamline at SSRF (Shanghai Synchrotron Radiation Facility). The temperature distribution, stress concentration effect, maximum equivalent (von-Mises) stress, and slope error of the mirror were analyzed. In particular, the cooling water channels of the traditional structural design were optimized, and the modified designs were further optimized. Although the traditional structural and the improved designs could meet requirements for the temperature and thermal stress, the deformation gradients were relatively large for several structural designs, and this led to larger slope error. The further improved structural designs could be of better performance.

Mechanical strength assessment of a drilled hole in the contralateral cortex at the end of the open wedge for high tibial osteotomy

BackgroundThis study aimed to investigate, by means of finite element analysis, the effect of a drill hole at the end of a horizontal osteotomy to reduce the risk of lateral cortex fracture while performing an opening wedge high tibial osteotomy (OWHTO). The question was whether drilling a hole relieves stress and increases the maximum correction angle without fracture of the lateral cortex depending on the ductility of the cortical bone.MethodsTwo different types of osteotomy cuts were considered; one with a drill hole (diameter 5 mm) and the other without the hole. The drill holes were located about 20 mm distally to the tibial plateau and 6 mm medially to the lateral cortex, such that the minimal thickness of the contralateral cortical bone was 5 mm. Based on finite element calculations, two approaches were used to compare the two types of osteotomy cuts considered: (1) Assessing the static strength using local stresses following the idea of the FKM-guideline, subsequently referred to as the “FKM approach” and (2) limiting the total strain during the opening of the osteotomy wedge, subsequently referred to as “strain approach”. A critical opening angle leading to crack initiation in the opposite lateral cortex was determined for each approach and was defined as comparative parameter. The relation to bone aging was investigated by considering the material parameters of cortical bones from young and old subjects.ResultsThe maximum equivalent (von-Mises) stress was smaller for the cases with a drill hole at the end of the osteotomy cut. The critical angle was approximately 1.5 times higher for the specimens with a drill hole compared to those without. This corresponds to an average increase of 50%. The calculated critical angle for all approaches is below 5°. The critical angle depends on the used approach, on patient’s age and assumed ductility of the cortical bone.ConclusionsDrilling a hole at the end of the osteotomy reduces the stresses in the lateral cortex and increases the critical opening angle prior to cracking of the opposite cortex in specimen with small correction angles. But the difference from having a drill hole or not is not so significant, especially for older patients. The ductility of the cortical bone is the decisive parameter for the critical opening angle.

Further study on the wheel–rail impact response induced by a single wheel flat: the coupling effect of strain rate and thermal stress

ABSTRACTA comprehensive dynamic finite-element simulation method was proposed to study the wheel–rail impact response induced by a single wheel flat based on a 3-D rolling contact model, where the influences of the structural inertia, strain rate effect of wheel–rail materials and thermal stress due to the wheel–rail sliding friction were considered. Four different initial conditions (i.e. pure mechanical loading plus rate-independent, pure mechanical loading plus rate-dependent, thermo-mechanical loading plus rate-independent, and thermo-mechanical loading plus rate-dependent) were involved into explore the corresponding impact responses in term of the vertical impact force, von-Mises equivalent stress, equivalent plastic strain and shear stress. Influences of train speed, flat length and axle load on the flat-induced wheel–rail impact response were discussed, respectively. The results indicate that the maximum thermal stresses are occurred on the tread of the wheel and on the top surface of the middle rail; the strain rate hardening effect contributes to elevate the von-Mises equivalent stress and restrain the plastic deformation; and the initial thermal stress due to the sliding friction will aggravate the plastic deformation of wheel and rail. Besides, the wheel–rail impact responses (i.e. impact force, von-Mises equivalent stress, equivalent plastic strain, and XY shear stress) induced by a flat are sensitive to the train speed, flat length and axle load.

Structural analysis of inclined type subsoiler using CAD software

Proper design of agriculture implements is necessary in order to increase their working life time and reduce the farming costs. In this study Creo and ANSYS software were used to carry out finite element analysis of inclined type subsoiler. 3D model of inclined type subsoiler was made using Creo software and static structural analysis of subsoiler was carried out using ANSYS software. The dimensions of inclined type subsoiler was selected as per local manufacturing database of subsoiler whereas loading condition defined by maximum draft force which was exerted on inclined type subsoiler in field. Results of simulation showed that maximum deformation was observed as 2.74 mm at the end of the share while maximum equivalent (von-mises) stress was 280.71MPa at the clamp. Maximum principal stress and maximum shear stress were found as 283.30MPa and 46.24MPa, respectively in subsoiler. The value of factor of safety was 1.25 and it was observed that factor of safety was very low so optimized design is required.

Comparison of Hydrostatic Extrusion between Pressure-Load and Displacement-Load Models

Two finite element analysis (FEA) models simulating hydrostatic extrusion (HE) are designed, one for the case under pressure load and another for the case under displacement load. Comparison is made of the equivalent stress distribution, stress state ratio distribution and extrusion pressure between the two models, which work at the same extrusion ratio (R) and the same die angle (2α). A uniform Von-Mises equivalent stress gradient distribution and stress state ratio gradient distribution are observed in the pressure-load model. A linear relationship is found between the extrusion pressure (P) and the logarithm of the extrusion ratio (lnR), and a parabolic relationship between P and 2α, in both models. The P-value under pressure load is smaller than that under displacement load, though at the same R and α, and the difference between the two pressures becomes larger as R and α grow.

FINITE ELEMENT ANALYSIS OF CONVENTIONAL REINFORCED CONCRETE AND STEEL FIBRE REINFORCED CONCRETE IN SLAB-COLUMN JOINT

Flat slabs are widely used in construction due to its architectural flexibility, good aesthetic view, uncomplicated formwork and less construction time. But as we know that under the large axial loads, gravity loads and seismic loads the flat slab is poor in resisting the punching shear which causes slab-column joint failure and further results in the collapse of the structure, so there is a need to improve flat slab performance. In this particular study the Flat slab building G+12 is modeled, analyzed and designed as per IS 456:2000 by considering suitable load conditions under seismic zone IV as per IS 1893:2002 in E-Tabs software. An interior column strip slabcolumn joint is considered and designed in ETabs and SAFE for the column and slab respectively. Analytical modeling of column strip slab of 2500x2500mm and column dimension of 500x600mm having a height of 1500mm is done in ANSYS. The boundary condition of the slab is simply supported at all sides and the column is pinned at both upper and lower face. The conventional reinforced slab and Steel Fibre reinforced Self-Compacting concrete slab properties are taken and fed into the ANSYS workbench and Linear static analysis to carry out the column strip slab-column joint behavior against axial loads, reaction force, gravity loads and lateral loads. The Total Deformation, Equivalent Von-mises stresses and Equivalent Elastic strain in slab and the slab-column joint are studied and compared. For SFRSCC slab used in slab-column joint shows almost 15% less Total Deformation of the structure compared to Conventional RC slab against the Axial and gravity loads, whereas during the lateral loads it almost twice effective as compared to conventional RC slab. Similarly the stresses and strains are reduced to large extent in SFRSCC slab which make it better material when used in joint which increases its performance.

Effect of temperature and pressure on stress of impeller in axial-centrifugal combined compressor

Axial-centrifugal combined compressors are commonly used, and the stresses of their impeller are important and influenced by temperature and pressure. The effects of temperature and pressure on the stresses of the impeller with different inlet conditions are investigated. Conjugate heat transfer analysis and three-dimensional structural finite element analysis are used to get the stresses of the impeller. The effects of temperature and pressure are obtained by comparing the equivalent (Von-Mises) stresses between cases taking and not taking them into account. From the result, the temperature effect is surprisingly large for low inlet temperature, reaching 57% of the total equivalent stress, and should be carefully considered. The effect strongly relates with the inlet conditions and the disk thermal boundary conditions. Thus, the later can’t be treated as adiabatic as usual. For certain inlet conditions, the stress of the impeller can be improved by adjusting the disk thermal boundary conditions. In addition, the temperature mainly affects the stress on the disk and the root of the blade. The pressure effect is small for low inlet temperature and can be sufficiently large for high inlet temperature. Furthermore, the pressure mainly influences the stress on the blade part and can reduce the stresses at the inducer of a negative-lean impeller.

Three-Dimensional Finite Element Analysis Surface Stress Distribution on Regular and Short Morse Taper Implants Generated by Splinted and Nonsplinted Prostheses in the Rehabilitation of Various Bony Ridges.

This study used finite element analysis to compare the biomechanical performance of splinted (SP) and nonsplinted (NSP) prostheses to regular and short length Morse taper implants in the posterior side of the mandible. The authors used 3-dimensional geometric models of regular implants (∅4 × 11 mm) and short implants (∅4 × 5 mm) housed in the corresponding bone edges of the posterior left mandibular hemiarch involving tooth 34. The 8 experimental groups were: the control group SP (3 regular implants rehabilitated with SP), group 1SP (2 regular and 1 short implants rehabilitated with SP), group 2SP (1 regular and 2 short implants rehabilitated with SP), group 3SP (3 short implants rehabilitated with SP), the control group NSP (3 regular implants rehabilitated with NSP), group 1NSP (2 and 1 short implants rehabilitated with NSP), group 2NSP (1 regular and 2 short implants rehabilitated with NSP), and group 3NSP (3 short implants rehabilitated with NSP). Oblique forces were simulated in the molars (365 N) and premolars (200 N). Qualitative and quantitative analysis of the distribution of Von Mises equivalent stress (implants, components, and infrastructure) was performed using the AnsysWorkbench10.0 software. The results showed that the use of SP provides several advantages and benefits, reducing the stresses placed on the implant surface, on the transmucosal abutment areas and on the interior region of the infrastructure. The use of NSP was advantageous in reducing the stresses on the abutments and in the distal interproximal area of connection between the crowns.

A numerical analysis of non–linear contact tasks for the system of plates with a bolted connection and a clearance in the fixture

The article presents an analysis of geometrically nonlinear contact tasks for the system of plates. The peculiarities of the presented tasks consist in research of a pressure-deformed state of two plates connected with a bolt fixture with a clearance and loaded with a uniformly distributed transverse force along the upper edge. Both geometrical and structural non-linearities are presented in the study tasks. The geometrically nonlinear formulation determines the SSS for plates connected with a bolt fixture with a clearance. Maximum deformation of such plates is 0.028 m and the equivalent (von-Mises) stress is 1200 MPa. The bolt skewing and the plate deformation increase tensile forces in the bolt, thereby increasing the force of the bolt fixture tightening (1500 N to 4000 N). The proposed methodology can be used for solving similar tasks as it considers a wide range of operating loads. In case when the researched object is a solid plate, geometrically linear and non-linear formulations do not guarantee reliable results.

Pressure stresses generated due to supersonic steam jet induced hydrodynamic instabilities

The phenomenon that involves direct contact of steam with water is called Direct Contact Condensation (DCC). This phenomenon has been observed/prevailed in most of the power and process industries. The phenomenon of direct contact condensation involves heat, mass and momentum transfer across the highly fluctuating interface between steam jet and surrounding water giving this process an intricate nature to be studied. More recently the observation of hydrodynamic instabilities at the interface between supersonic steam jet and water has given a new facet to the study of DCC. In the current study the equivalent von-Mises Stress, equivalent elastic strain and total deformation in the Perspex vessel that has been incurred due to the pressure stresses has been studied. These pressure stresses have been generated due to the condensing supersonic steam jet induced hydrodynamic instabilities. It has been investigated first by experimentally observing the temperature fluctuations in axial and radial directions across supersonic steam jet which actually depicts these instabilities. Then Direct Contact Condensation (DCC) model has been used to conduct the CFD study using a commercial code Ansys®. Accompanied with this a mock up study has been done in which the pressure loads computed using DCC model have been coupled to the Perspex vessel structure using one way Fluid Structure Interaction (FSI) analysis in Ansys® to compute the true scale equivalent von-Mises Stress, equivalent elastic strain and total deformation generated by hydrodynamic instabilities induced pressure stresses. On true scale, hundreds of Pico scale deformation has been computed in the Perspex vessel confinement.

Stress and stability of plate-screw fixation and screw fixation in the treatment of Schatzker type IV medial tibial plateau fracture: a comparative finite element study.

PurposeThe purpose of this study is to compare the stress and stability of plate-screw fixation and screw fixation in the treatment of Schatzker type IV medial tibial plateau fracture.MethodsA three-dimensional (3D) finite element model of the medial tibial plateau fracture (Schatzker type IV fracture) was created. An axial force of 2500 N with a distribution of 60 % to the medial compartment was applied to simulate the axial compressive load on an adult knee during single-limb stance. The equivalent von Mises stress, displacement of the model relative to the distal tibia, and displacement of the implants were used as the output measures.ResultsThe mean stress value of the plate-screw fixation system was 18.78 MPa, which was significantly (P < 0.001) smaller than that of the screw fixation system. The maximal value of displacement (sum) in the plate-screw fixation system was 2.46 mm, which was lower than that in the screw fixation system (3.91 mm). The peak stress value of the triangular fragment in the plate-screw fixation system model was 42.04 MPa, which was higher than that in the screw fixation model (24.18 MPa). But the mean stress of the triangular fractured fragment in the screw fixation model was significantly higher in terms of equivalent von Mises stress (EVMS), x-axis, and z-axis (P < 0.001).ConclusionsThis study demonstrated that the load transmission mechanism between plate-screw fixation system and screw fixation system was different and the stability provided by the plate-screw fixation system was superior to the screw fixation system.

The influence of scanning methods on the cracking failure of thin-wall metal parts fabricated by laser direct deposition shaping

In order to improve the quality of thin-wall metal parts fabricated by laser direct deposition shaping method, using “element birth and death” technique, a three-dimensional multitrack and multilayer thin-wall model was developed. Different scanning methods, including long-edge parallel reciprocating scanning, short-edge parallel reciprocating scanning and inter-layer orthogonal parallel reciprocating scanning, were researched. The Von Mises equivalent stress, and its X-directional, Y-directional and Z-directional principal stresses were analyzed in detail. Under the same conditions used in the simulations, the deposition experiments were conducted, and the influence of different scanning methods on the cracking failure behavior of thin-wall metal parts was discussed.