Structural Stress Determination at a Hot-Spot

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Goeun Han ◽  
Sukru Guzey
Keyword(s):  
Finite Element ◽  
Hot Spots ◽  
Hot Spot ◽  
Single Point ◽  
Equivalent Stress ◽  
Peak Stress ◽  
Element Model ◽  
Cauchy Stress ◽  
Structural Stress ◽  
Element Analysis

Abstract Stress analysis by a finite element analysis program sometimes causes singularities in hot-spots. In a failure assessment, the structural stress, and membrane and bending stress should be determined in a highly stressed spot (hot-spot). When the structural stress at a hot-spot is disturbed by singularities, the stress result not only diverges, by reducing the element size, but also shows a decreased value compared to nominal stress because the stress is substituted into the von Mises equivalent stress equation. In the three-dimensional (3D) finite element model, it is hard to avoid the singularity problem at hot-spots particularly when it is subjected to loads in three axial directions. For the alternative, this study converts the 3D model into two-dimensional (2D) plane models to remove the singularity and to obtain reasonable structural stress values excluding the peak stress. The structural stress-estimating approaches applied in the 2D model were examined for whether they could avoid the structural stress reduction near the hot-spot with mesh insensitivity. The implemented approaches are stress linearization, single point away method, stress equilibrium, stress extrapolation, and the nodal force method. The results computed by each approach are compared and reconstructed to 3D stress by the Cauchy stress matrix. This study found that the difference in structural stress in 2D was eliminated after the 3D stress reconstruction.

Finite element analysis and structural design of axially uniform-loaded nut

2017 ◽  
Vol 52 (4) ◽  
pp. 215-225
Author(s):  
Zhao Chun-jiang ◽  
Liu Yong-feng ◽  
Zhang Fei-tao ◽  
Wang Zheng-yi ◽  
Gui Hai-lian
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Model ◽  
Equivalent Stress ◽  
Peak Stress ◽  
Element Model ◽  
Working Process ◽  
Element Analysis ◽  
Finite Element Software ◽  
Heavy Equipment

Axially heavy-loaded screw pairs are widely used in rolling mill press systems and other heavy equipment. During the working process, the nut is pressed at both ends, which causes equivalent stress at the thread roots in a U-shaped distribution along the height. Thread roots at the ends tend to suffer fracture failure when the equivalent stress is too great. In this article, the finite element software ANSYS is used to establish a 3D model of screw pairs and analyse bearing characteristics. A new structure based on the results of finite element analysis, which improves U-shaped stress distribution, is proposed for the axially uniform-loaded nut, with a different strain–displacement relationship between the nut matrix and the thread teeth. Such a relationship can greatly reduce peak stress at the thread roots of the nut on both ends. Experiments are conducted on the nut using the electrometric method. Results are compared with the finite element results to directly verify the reliability of the finite element model of ordinary screw pairs and indirectly verify the reliability of the structural model of new screw pairs.

The effects of shape memory alloys’ tension–compression asymmetryon NiTi endodontic files’ fatigue life

2018 ◽  
Vol 232 (5) ◽  
pp. 437-445 ◽  
Author(s):  
MR Karamooz-Ravari ◽  
R Dehghani
Keyword(s):  
Finite Element ◽  
Shape Memory ◽  
Numerical Models ◽  
Equivalent Stress ◽  
Element Model ◽  
Niti Shape Memory Alloy ◽  
Element Analysis ◽  
Tension And Compression ◽  
Von Mises Equivalent Stress ◽  
Von Mises

Nowadays, NiTi rotary endodontic files are of great importance due to their flexibility which enables the device to cover all the portions of curved canal of tooth. Although this class of files are flexible, intracanal separation might happen during canal preparation due to bending or torsional loadings of the file. Since fabrication and characterization of such devices is challenging, time-consuming, and expensive, it is preferable to predict this failure before fabrication using numerical models. It is demonstrated that NiTi shape memory alloy shows asymmetric material response in tension and compression which can significantly affect the lifetime of the files fabricated from. In this article, the effects of this material asymmetry on the bending response of rotary files are assessed using finite element analysis. To do so, a constitutive model which takes material asymmetry into account is used in combination with the finite element model of a RaCe file. The results show that the material asymmetry can significantly affect the maximum von Mises equivalent stress as well as the force–displacement response of the tip of this file.

The Finite Element Analysis on the Compression Splicing Position of Strain Clamp in Guy Tower

2014 ◽  
Vol 680 ◽  
pp. 249-253
Author(s):  
Zhang Qi Wang ◽  
Jun Li ◽  
Wen Gang Yang ◽  
Yong Feng Cheng
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Finite Element Model ◽  
Equivalent Stress ◽  
Element Model ◽  
Element Analysis ◽  
Elastic Plastic ◽  
The Finite Element Analysis

Strain clamp is an important connection device in guy tower. If the quality of the compression splicing position is unsatisfied, strain clamp tends to be damaged which may lead to the final collapse of a guy tower as well as huge economic lost. In this paper, stress distribution on the compressible tube and guy cable is analyzed by FEM, and a large equivalent stress of guy cable is applied to the compression splicing position. During this process, a finite element model of strain clamp is established for guy cables at compression splicing position, problems of elastic-plastic and contracting are studied and the whole compressing process of compressible position is simulated. The guy cable cracks easily at the position of compressible tube’s port, the inner part of the compressible tube has a larger equivalent stress than outside.

Finite Element Analysis of the Influence of Balance Mode on Rolling Mill Universal Spindle Strength

2014 ◽  
Vol 548-549 ◽  
pp. 449-453 ◽  
Author(s):  
Zhi Qiang Guo ◽  
Ze Lu Xu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Model ◽  
Rolling Mill ◽  
Loading Condition ◽  
Equivalent Stress ◽  
Bending Moment ◽  
Element Model ◽  
Element Analysis ◽  
Universal Spindle

For the problem of balance bearing of universal spindle in rolling mill being prone to damage, the paper established mechanical model and finite element model of universal spindle. The paper has analyzed that the shear and bending moment in the middle of the shaft is the largest. The fillet near shoulder of balance bearing of the spindle is dangerous part. In order to reduce principal stress of universal spindle caused by moment, the paper improved balance mode of the spindle. The equilibrant was applied from in one place of shaft to put in two places. After optimizing, equivalent stress of the spindle is slight smaller than before under the same loading condition, which illustrates that the strength of the spindle is appropriately improved. Although the effect is not obvious, this has played a guiding role for the optimization of balance mode of universal spindle.

Finite Element Analysis of Hydraulic Clipping Machine Shear Platform Dased on ANSYS

2014 ◽  
Vol 945-949 ◽  
pp. 190-193
Author(s):  
Hai Lin Wang ◽  
Yi Hua Sun ◽  
Ming Bo Li ◽  
Gao Lin ◽  
Yun Qi Feng ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Elastic Strain ◽  
Optimization Design ◽  
Equivalent Stress ◽  
Element Model ◽  
Element Analysis ◽  
Maximum Equivalent Stress

Q43Y-85D type crocodile hydraulic clipping machine was taken as research object to optimization design. A finite element model for clipping machine was built using shell unit as fundamental unit. ANSYS12.0 finite element method was used to analyze the deformation and stress distribution of the shear platform model of hydraulic clipping machine. The result showed that the maximum equivalent stress at the dangerous area was 368.162 MPa and the maximum elastic strain was 0.1814×10-2 mm. After the structural optimization design, it was found that the maximum equivalent stress decreased to 186.238 MPa which did not exceed the material’s yield limitation 215 MPa and the maximum elastic strain decreased to 0.919×10-3 mm which satisfied the requirement of stiffness.

Finite Element Analysis of Cold Expanding of Hollow Thin-Wall Tube

2011 ◽  
Vol 460-461 ◽  
pp. 44-47
Author(s):  
Wei Hua Kuang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Distribution ◽  
Equivalent Stress ◽  
Element Model ◽  
Thin Wall ◽  
Forming Process ◽  
Element Analysis ◽  
Simulation Step ◽  
The Finite Element Analysis

The cold expanding diameter process was simulated by the software of DEFORM. The finite element model of tube and dies were built. The object position definition, the inter object setting, movement definition and simulation step were correctly set. The deformation, total velocity distribution and equivalent stress distribution were predicted. The numerical simulation results showed that the finite element analysis could exactly describe the plastic deformation and stress distribution during the forming process.

Effects of Local Peak Stress Distribution on the Ratchet Limit

2002 ◽  
Author(s):  
Nobuyoshi Yanagida ◽  
Masaaki Tanaka ◽  
Norimichi Yamashita ◽  
Yukinori Yamamoto
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Plastic Strain ◽  
Equivalent Stress ◽  
Equivalent Plastic Strain ◽  
Peak Stress ◽  
Element Analysis ◽  
Stress Evaluation ◽  
Elastic Plastic ◽  
Plastic Analysis

Alternative stress evaluation criteria suitable for Finite Element Analysis (FEA) proposed by Okamoto et al. [1],[2] have been studied by the Committee on Three Dimensional Finite Element Stress Evaluation (C-TDF) in Japan. Thermal stress ratchet criteria in plastic FEA are now under consideration. Two criteria are proposed: (1) Evaluating variations in plastic strain increments, and (2) Evaluating the width of the area in which Mises equivalent stress exceeds 3Sm. To verify of these criteria, we selected notched cylindrical vessel models as prime elements. To evaluate the effect of the local peak stress distribution on these criteria, cylindrical vessels with a semicircular notch on the outer surface were selected for this analysis. We used two notch configurations for our analysis, and the stress concentration factor for the notches was set to 1.5 and 2.0. We conducted elastic-plastic analysis to evaluate the ratchet limit. Sustained pressure and alternating enforced longitudinal displacements which causes secondary stress were used as parameters for the elastic-plastic analysis. We found that when no ratchet was observed, the equivalent plastic strain increments decreased and the area in which Mises equivalent stress exceeds 3Sm are below the certain range.

Rational Stress Limits and Load Factors for Finite Element Analyses in Pipeline Applications: Part I—Linear Elastic Stress Limit Development

2010 ◽  
Author(s):  
Bisen Lin ◽  
Richard C. Biel
Keyword(s):  
Finite Element ◽  
Equivalent Stress ◽  
Element Model ◽  
Element Analysis ◽  
Linear Elastic ◽  
Stress Limit ◽  
Load Factors ◽  
End Conditions ◽  
Von Mises Equivalent Stress ◽  
Von Mises

In this paper, a rational stress limit based on the von Mises equivalent stress is established for pipelines subjected to internal pressure. This stress limit is based on the ASME pipeline Code’s design margin for the service and location of the installation [1, 2]. These Codes are recognized by 49 CRF192 [5]. Both capped-end and open end conditions are considered. The single value of stress limits can be derived by classical hand calculations for use in assessing the results of a finite element analysis (FEA). Two application examples are presented showing studies done with the ABAQUS [3], a commercial (FEA) software. A stress limit was first found using classical hand calculations and verified by a simple finite element model. The linearized stresses at some critical locations were then compared to the established stress limit, and multiples, for the assessments of membrane, membrane plus bending, etc. stresses. This paper is not intended to revise or replace any provision of ASME B31.8 [2]. Instead, it provides a rational stress limit that may be used in the assessment of detailed FEA analyses of pipelines and the associated components.

scholarly journals A Novel Anatomical Self-locking Plate Fixation for Both-column Acetabular Fractures: - Finite Element Analysis

2021 ◽  
Author(s):  
Ming Li ◽  
Ding Xu ◽  
Yong Zhang ◽  
Bo Chen ◽  
Haiyang Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Locking Plate ◽  
Plate Fixation ◽  
Peak Stress ◽  
Element Model ◽  
Implant Failure ◽  
Acetabular Fractures ◽  
Reconstruction Plate ◽  
Element Analysis ◽  
Fixation Methods

Abstract Background: Both-column acetabular fractures often require multiple plates for fixation, and the risk of internal implant failure is high. The author designed a posterior anatomic self-locking plate (PASP) to avoid the shortcomings. The stability of PASP was compared with two popular reconstruction plate fixation methods, and the influence of sitting, turning right and left on implants were explored. Methods: PASP, double reconstruction plate (DRP), and cross reconstruction plate (CRP) were assembled on the finite element model of both-column fractures of the left acetabulum. A load of 600N and a torque of 8N·m were loaded on the S1 vertebral body to detect stress and displacement changes when sitting, turning right and left. Results: The peak stress and displacement of three types of fixation methods on the left both-column fractures under three types of movements were CRP > DRP > PASP. PASP has the minimal value when turning left. The maximum peak of stress and displacement of PASP are 313.5 MPa and 1.15 mm respectively when turning right. Conclusion: PASP can provide higher stability than two reconstruction plates for both-column acetabular fractures. The rational movement after posterior DRP and PASP fixation for acetabular fracture is to turn to the ipsilateral side, which can avoid implant failure.

scholarly journals An Investigation into Scalpel Blade Sharpness Using Cutting Experiments and Finite Element Analysis

2005 ◽  
Vol 293-294 ◽  
pp. 769-776 ◽  
Author(s):  
C.T. McCarthy ◽  
M. Hussey ◽  
Michael D. Gilchrist
Keyword(s):  
Finite Element ◽  
Substrate Surface ◽  
Peak Stress ◽  
Element Model ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Sharpness Measurement ◽  
Blade Tip ◽  
Scalpel Blade ◽  
Von Mises

This paper presents an investigation into the sharpness of a surgical scalpel blade. An experiment was carried out in which a surgical scalpel blade was pushed through an elastomeric substrate at a constant velocity. The force-displacement characteristics were examined by plotting the stiffness as a function of blade displacement and it was found that this curve could clearly identify the point where the material separates to form a cut. A blade sharpness measurement was defined as the energy required to initiate an opening or cut in the substrate. A finite element model was developed to examine the stress state in the substrate at the point where the opening initiates. The development of this model is described. The model was validated against the experiment and close agreement was obtained. The von-Mises stress distribution under the blade tip was plotted and it was shown that the peak stress actually occurs away from the blade tip, suggesting that material separation would initiate away from the substrate surface.

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