Study of a Specimen with Stress Concentrators in Multiaxial Tests

2015 ◽  
Vol 809-810 ◽  
pp. 974-979 ◽  
Author(s):  
Ana Maria Comanici ◽  
Viorel Goanta ◽  
Paul Doru Barsanescu ◽  
Liviu Andrusca
Keyword(s):  
Experimental Investigation ◽  
Stress State ◽  
Accurate Information ◽  
Stress Concentrations ◽  
State Distribution ◽  
Element Analysis ◽  
Investigation Methods ◽  
Methods And Techniques ◽  
Limit Stress ◽  
Distribution Of Stresses

Experimental investigation methods and techniques are used to obtain accurate information on the tension and deformation of materials. Results underlying the limit stress state that aply to materials at this moment come from experiments on plain specimens and specimens showing stress concentrations. The study of stress concentrations is necessary to determine how it influences the limit stress state, distribution of stresses and yielding section. The article presents a series of specimens with stress concentrations and finite element analysis for thorough research.

Influence of Aggregate Stiffness on Fracture-Mechanical Properties of Lime-Based Mortars

2013 ◽  
Vol 486 ◽  
pp. 289-294 ◽  
Author(s):  
Pavel Tesárek ◽  
Václav Nežerka ◽  
Pavel Padevět ◽  
Jakub Antoš ◽  
Tomáš Plachy
Keyword(s):  
Experimental Investigation ◽  
Finite Element ◽  
Damage Model ◽  
Element Model ◽  
Stress Concentrations ◽  
Damage Development ◽  
Element Analysis ◽  
Three Point Bending ◽  
Isotropic Damage ◽  
The Finite Element Model

Addition of relatively stiff aggregates into lime-based mortars is responsible for an increase of the effective mortar stiffness and stress concentrations around aggregates during mechanical loading. To observe the damage development during the three-point bending and splitting tests a 2D plane-stress nonlinear finite element analysis utilizing isotropic damage model was carried out and the results were validated against experimentally obtained data. The study revealed that the finite element model is able to capture the trends observed during the experimental investigation. The results of the numerical modeling and experimental investigation show the advantages of the use of relatively compliant crushed brick aggregates in ancient structures.

Detailed stress analysis of a twill orthogonally woven textile composite

2020 ◽  
Vol 54 (25) ◽  
pp. 3801-3820
Author(s):  
M Keith Ballard ◽  
John D Whitcomb
Keyword(s):  
Stress State ◽  
High Performance ◽  
Small Region ◽  
Stress Distributions ◽  
Severe Stress ◽  
Stress Concentrations ◽  
Textile Composite ◽  
Element Analysis ◽  
Sharp Edges ◽  
Woven Textile

A finite element analysis framework that leverages high-performance computing was used to analyze a twill orthogonally woven textile model. Boundary conditions for uniaxial tension along the warp direction were applied to a large analysis region, and an interior subregion was used for investigating the stress distributions. The locations of severe stresses were investigated for the binders, wefts, warps, and matrix, respectively, and the connection of the stress state to the surrounding tow architecture was discussed. It was shown that the highest stresses developed in the binders where the path of a binder changed direction, due to a transfer of load to nearby wefts that induced a severe shear stress in the binder. Additionally, severe stress concentrations were observed in both the wefts and binders where the binders traversed the thickness of the textile and came near a weft. The magnitude of the concentration in the binders closely matched across similar locations. On the other hand, the concentrations in the weft appeared to be sensitive to the faceted surfaces of the tows, which sometimes resulted in sharp edges, but these stress the concentrations in the wefts did remain localized. In the warps, the normal stress in the direction of the load was the largest, but the most severe stress state was shown to occur in a very small region where warps came close to binders as the path of the binder transitioned.

scholarly journals Effect of Crown Shape of Rolls on the Distribution of Stress and Elastic Deformation for Rolling Processes

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1222
Author(s):  
Rumualdo Servin ◽  
Sixtos A. Arreola ◽  
Ismael Calderón ◽  
Alejandro Perez ◽  
Sandra M. San Miguel
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Maximum Stress ◽  
Work Roll ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Crown Shape ◽  
Properties Of Materials ◽  
Distribution Of Stress ◽  
Distribution Of Stresses

The present work analyzes the influence of crown shape on the distribution of stresses and deformation for rolling processes. This study consists of a Finite Element Analysis considering combinations of crown shape for Back Up Roll and Work Roll, rolling forces, properties of materials and dimensions of rolls and strip. An analysis of the rolls based on a double cantilever model with the fulcrum of the beams in a centerline mill was carried out. The results show that maximum stress concentrations for all combinations of crown shape analyzed appear on both sides 787.4 mm from the mill centerline, exactly on the sides of the strip. In this area, the maximum stress for the best combination of crown shape is larger than in the centerline mill, increasing from 34.2 MPa to 163.0 MPa. This is proportional according to Hooke’s law for which strain of rolls increases from 3.4067 × 10−4 to 4.8368 × 10−4. The worst combinations of crown shapes were obtained when the shapes of the barrel are the same for the BUR and WR; for example: Combination 1 (BUR Positive–WR Positive), Combination 5 (BUR Flat–WR Flat), and Combination 9 (BUR Negative–WR Negative).

Effective Convergence Checks for Verifying Finite Element Stresses at Three-Dimensional Stress Concentrations

2018 ◽  
Vol 3 (3) ◽  
Author(s):  
J. R. Beisheim ◽  
G. B. Sinclair ◽  
P. J. Roache
Keyword(s):  
Finite Element ◽  
Error Estimation ◽  
A Posteriori Error Estimates ◽  
Three Dimensional ◽  
Posteriori Error ◽  
Test Problems ◽  
A Posteriori ◽  
Stress Concentrations ◽  
Element Analysis ◽  
A Posteriori Error

Current computational capabilities facilitate the application of finite element analysis (FEA) to three-dimensional geometries to determine peak stresses. The three-dimensional stress concentrations so quantified are useful in practice provided the discretization error attending their determination with finite elements has been sufficiently controlled. Here, we provide some convergence checks and companion a posteriori error estimates that can be used to verify such three-dimensional FEA, and thus enable engineers to control discretization errors. These checks are designed to promote conservative error estimation. They are applied to twelve three-dimensional test problems that have exact solutions for their peak stresses. Error levels in the FEA of these peak stresses are classified in accordance with: 1–5%, satisfactory; 1/5–1%, good; and <1/5%, excellent. The present convergence checks result in 111 error assessments for the test problems. For these 111, errors are assessed as being at the same level as true exact errors on 99 occasions, one level worse for the other 12. Hence, stress error estimation that is largely reasonably accurate (89%), and otherwise modestly conservative (11%).

scholarly journals Evaluation of Different Restoration Combinations Used in the Reattachment of Fractured Teeth: A Finite Element Analysis

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Nagihan Guven ◽  
Ozgur Topuz ◽  
İhsan Yikilgan
Keyword(s):  
Finite Element Analysis ◽  
Glass Fiber ◽  
Composite Resin ◽  
Fracture Line ◽  
Core Material ◽  
Fiber Post ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Composite Resin Restoration ◽  
Glass Fiber Post

Objective. The purpose of this study was to test different restoration combinations used for constructing fractured endodontically treated incisors by reattaching their fractured fragments. Methods. Seven types of 3-D FEM mathematical root canal-filled models were generated, simulating cases of (OB) reattaching fractured fragments; (CrPL) reattaching fractured fragments + ceramic palatinal laminate; (CmPL) reattaching fractured fragments + composite palatinal laminate; (CM) reattaching fractured fragments + coronal 1/3 of the root was filled using core material; (BP) reattaching fractured fragments + glass fiber post; (CP) composite resin restoration + glass fiber post; and (OC) composite resin restoration. A 100-N static oblique force was applied to the simulated teeth with 135° on the node at 2 mm above the cingulum to analyze the stress distribution at the tooth. Results. For enamel tissue, the highest stress values were observed in model BP, and the lowest stress values were observed in model CmPL. For dentine tissue, the highest stress concentrations were observed around the fracture line for all models. Conclusions. Reattachment of fractured fragments by bonding may be preferred as a restoration option for endodontically treated incisors; also, palatinal laminate decreases the stress values at tooth tissues, especially at the enamel and the fracture line.

Practical Procedures for Technical and Economic Investigation of Ship Structural Details

1981 ◽  
Vol 18 (01) ◽  
pp. 51-68
Author(s):  
Donald Liu ◽  
Abram Bakker
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Analysis Techniques ◽  
Structural Problems ◽  
Analysis Technique ◽  
The Finite Element Analysis ◽  
Structural Details

Local structural problems in ships are generally the result of stress concentrations in structural details. The intent of this paper is to show that costly repairs and lay-up time of a vessel can often be prevented, if these problem areas are recognized and investigated in the design stages. Such investigations can be performed for minimal labor and computer costs by using finite-element analysis techniques. Practical procedures for analyzing structural details are presented, including discussions of the results and the analysis costs expended. It is shown that the application of the finite-element analysis technique can be economically employed in the investigation of structural details.

Computer-Aided Gear Product Realization

2018 ◽  
Author(s):  
Alireza Yazdanshenas ◽  
Emilli Morrison ◽  
Chung-Hyun Goh ◽  
Janet K. Allen ◽  
Farrokh Mistree
Keyword(s):  
Computer Aided Design ◽  
Interaction Analysis ◽  
Gear Tooth ◽  
Integrated Design ◽  
System Level ◽  
Trial And Error ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Gear Design ◽  
Computer Aided

To save time and resources, many are making the transition to developing their ideas virtually. Computer-aided gear production realization is becoming more and more desired in the industry. To produce gears with custom qualities, such as material, weight and shape, the trial and error approach has yielded the best results. However, trial and error is costly and time consuming. The computer-aided integrated design and manufacturing approach is intended to resolve these drawbacks. A simple one stage reduction spur gearbox is used as an example in a case study. First, the gear geometry is developed using computer aided design (CAD) modeling. Next, using MATLAB/Simulink, the gear assembly is connected virtually to other subsystems for system expectations and interaction analysis. Finally, using finite element analysis (FEA) tools such as ABAQUS, a dynamic FEA of the gear integration is completed to analyze the stress concentrations and gear tooth failures. Through this method of virtual gear design, customized dimensions and specifications of gears for satisfying system-level requirements can be developed, thereby saving time and manufacturing costs for any custom gear design request.

BIDIMENSIONAL FINITE ELEMENT ANALYSIS OF SPUR GEAR: STUDY OF THE MESH STIFFNESS AND STRESS AT THE LEVEL OF THE TOOTH FOOT

2009 ◽  
Vol 33 (2) ◽  
pp. 175-187 ◽  
Author(s):  
Mohamed Nizar Bettaieb ◽  
Mohamed Maatar ◽  
Chafik Karra
Keyword(s):  
Finite Element ◽  
Stress State ◽  
Spur Gear ◽  
Fortran Program ◽  
Mesh Stiffness ◽  
Element Analysis ◽  
Gear Mesh ◽  
Finite Element Software ◽  
Time Calculation ◽  
Finite Element Meshing

The purpose of this work is to determine the spur gear mesh stiffness and the stress state at the level of the tooth foot. This mesh stiffness is derived from the calculation of the normal tooth displacements: local displacement where the load is applied, tooth bending displacement and body displacement [15]. The contribution of this work consists in, basing on previous works, developing optimal finite elements model in time calculation and results precision. This model permits the calculation of time varying mesh stiffness and the evaluation of stress state at the tooth foot. For these reasons a specific Fortran program was developed. It permit firstly, to obtain the gear geometric parameters (base radii, outside diameter,…) and to generate the data base of the finite element meshing of a tooth or a gear. This program is interfaced with the COSMOS/M finite element software to predict the stress and strain state and calculate the mesh stiffness of a gear system. It is noted that the mesh stiffness is periodic and its period is equal to the mesh period.

Patient-Specific 3D Finite-Element Analysis of Miniscrew Implants During Orthodontic Treatment

2009 ◽  
Author(s):  
Hussein H. Ammar ◽  
Victor H. Mucino ◽  
Peter Ngan ◽  
Richard J. Crout ◽  
Osama M. Mukdadi
Keyword(s):  
Finite Element ◽  
Orthodontic Treatment ◽  
3D Model ◽  
Patient Specific ◽  
Stress Concentrations ◽  
Element Analysis ◽  
Miniscrew Implants ◽  
Operative Planning ◽  
Miniscrew Implant ◽  
Maximum Stresses

Miniscrew implants have seen increasing clinical use as orthodontic anchorage devices with demonstrated stability. The focus of this study is to develop and simulate operative factors, such as load magnitudes and anchor locations to achieve desired motions in a patient-specific 3D model undergoing orthodontic treatment with miniscrew implant anchorage. A CT scan of a patient skull was imported into Mimics software (Materialise, 12.1). Segmentation operations were performed on the images to isolate the mandible, filter out noise, then reconstruct a smooth 3D model. A model of the left canine was reconstructed with the PDL modeled as a thin solid layer. A miniscrew was modeled with dimensions based on a clinical implant (BMK OAS-T1207) then inserted into the posterior mandible. All components were volumetrically meshed and optimized in Mimics software. Elements comprising the mandible bone and teeth were assigned a material based on their gray value ranges in HU from the original scan, and meshes were exported into ANSYS software. All materials were defined as linear and isotropic. A nonlinear PDL was also defined for comparison. For transverse forces applied on the miniscrew, maximum stresses increased linearly with loading and appeared at the neck or first thread and in the cortical bone. A distal tipping force was applied on the canine, and maximum stresses appeared in the tooth at the crown and apex and in the bone at the compression surface. Under maximum loading, stresses in bone were sufficient for resorption. The nonlinear PDL exhibited lower stresses and deflections than the linear model due to increasing stiffness. Numerous stress concentrations were seen in all models. Results of this study demonstrate the potential of patient-specific 3D reconstruction from CT scans and finite-element simulation as a versatile and effective pre-operative planning tool for orthodontists.

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