Evaluation Of Stress Concentration Factors Research Articles

자켓 트러스 구조물 용접이음부 기하형상에 따른 응력집중계수 평가

자켓 트러스 구조물 용접이음부 기하형상에 따른 응력집중계수 평가

Performance Evaluation of Stress Concentration Factor for Shoulder Fillet on Round Bar under Bending Loading

In industries, many unexpected failures of machine components occurs due to lack of proper design, sudden changes that happen during working conditions and pre-existing geometrical irregularities. The geometric discontinuities cannot be avoided as they fulfill functional requirements. The shaft or round bar with shoulder fillet is one of the machine components working under different loading conditions. In the present work, shoulder filleted shaft/round bar working under bending loading conditions is taken for study and the stress concentration factor was evaluated. Finite element analysis (FEA) is performed for a total of seven different geometries with different D/d ratios and analyzed them using ANSYS 19.0 workbench software. Based on the equivalent (Von Mises) stresses obtained from the FEA, stress concentration factor (SCF) for the shoulder filleted shaft is calculated and compared with the theoretical results obtained from derived modified Pilkey’s equations, Roark’s equations, and S. M. Tipton equations. The outcome of results shows that for lower D/d ratios both results were identical in nature but for higher D/d ratios, the results found deviated. The SCFs are decreased with increasing D/d ratios. The results of SCFs are presented in the form of graphs for comparison purpose as well as one can refer it for his/her applications.

Atomistic evaluation of the stress concentration factor of graphene sheets having circular holes

Stress concentration factor concept has been developed for single-layered graphene sheets (SLGSs) with circular holes through an atomistic point of view by the application of molecular structural mechanics (MSM) approach. In this approach the response of SLGSs against unidirectional tensile loading is matched to the response of a frame-like macro structure containing beam elements by making an equivalence between strain energies of beam elements in MSM and potential energies of chemical bonds of SLGSs. Both chirality and size effects are considered and the atomistic evaluation of stress concentration factor is performed for different sizes of circular holes. Also, molecular dynamics simulations are implemented to verify the existence and location of the predicted stress concentration. The results reveal that size effects and the diameters of circular holes have a significant influence on the stress concentration factor of SLGSs and armchair SLGSs show a larger value of stress concentration than zigzag ones.

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Experimental, analytical, and finite element study of stress concentration factors for composite materials

This article focuses on the evaluation of stress concentration factors for composite materials with varying hole diameters. An innovative method is presented for measuring the stress concentration around a hole using the digital image correlation method. This method can provide a quicker and cheaper testing technique. The digital image correlation method is utilized to evaluate the strain field and the displacement at the edge of the hole and obtain information about fracture mechanisms in the studied materials. The effect of the ratio of the hole diameter to its width (a/w ratio) on both gross and net stress concentration factors around the hole is investigated. In addition, there is a comparison between the net and the gross stress concentration factors uses of the digital image correlation method, the analytical solutions, and the finite-element analysis for both composite and steel materials.

Experimental evaluation of stress concentration factor of welded steel bridge T-joints

This paper describes an experimental study on determining the stress concentration factor (SCF) and its stochastic characteristics for a typical welded steel bridge T-joint. A full-scale segment model, which holds the same profile with a railway beam section of the suspension Tsing Ma Bridge (TMB) in geometric dimension and material property as well as in weld details, is fabricated and tested. With the measurement data obtained from strain gauges deployed on the web and flanges, the hot spot strain at the weld toe is determined by a linear regression method. The SCF is then calculated as the ratio between the hot spot strain and the nominal strain which is obtained directly by measurement. To fully account for the effect of predominant factors on the scatter of SCF, the experiments are carried out under different moving load conditions. The statistical properties and probability distribution of SCF are derived, which reveals that the SCF for the welded steel bridge T-joint conforms to a normal distribution.

Evaluation of Stress Concentration Factor for a Double-Notched Plate

Evaluation of Stress Concentration Factor for a Double-Notched Plate

206 強度研究用切欠き試験片の応力集中係数の高精度評価に関する研究(材料力学I)

206 強度研究用切欠き試験片の応力集中係数の高精度評価に関する研究(材料力学I)

Evaluation of Stress Concentration Factor at Weld Toes in Welded Joints by Means of the Thermoelastic Stress Analysis

The stress concentration factor at a weld toe in a welded joint is a very important factor of fatigue strength in welded structures. Since the shapes of weld toes are individually different, it is not appropriate to evaluate stress concentration factors at weld toes using numerical analysis such as FEM. In order to evaluate practically and accurately stress concentration factors at weld toes, thermoelastic stress analysis method (TSA), which is a stress analysis technique based on the measurement of infrared emission from the surface of a body subjected to cyclic loading, was applied to the measurement of stress distributions near weld toes. In this study, stress concentration factors evaluated by TSA were extremely lower than comparable numerical results due to the resolution limit of the infrared camera used. When stress distributions near weld toes measured by TSA were corrected by the empirical equation using toe radius, stress concentration factors evaluated by TSA agreed with numerical values within 25%.

Evaluation of stress concentration factors and stress intensity factors from remote boundary data

Usually, the stress concentration factors (SCFs) for holes and the stress intensity factors (SIFs) for cracks are evaluated by using the data near holes or cracks. However, the abrupt change of the stresses near holes, especially near crack tips, may lead to an unavoidable error. Thus, it is always interesting to find an equivalent formulation for SCF and SIF by using only remote boundary responses (displacements, stresses and strains) cooperating with the necessary geometric data. Through a special boundary element formulation of which the fundamental solution was derived using Stroh’s formalism for two-dimensional anisotropic elasticity, all the internal stresses and strains can be expressed in terms of the boundary (not including the hole and crack boundaries) displacements and tractions. By proper mathematical manipulation, a closed form solution for SIF of the internal crack and SCF of the internal hole, expressed by using only remote boundary displacements and tractions, is derived in this paper. To show that the proposed formula is accurate and efficient, several numerical examples are presented.

Finite element evaluation of stress concentration factor of thick laminated plates under transverse loading

A displacement-based formulation of an isoparametric quadratic quadrilateral element for the analysis of thick laminated plates is presented with the help of Lo-Christensen-Wu higher order bending theory. The finite element formulation is then used for the analysis of in-plane stresses of a simply supported thick laminated plate containing two circular holes under transverse sinusoidal loading. The results obtained by this theory compare favourably with the exact elasticity solutions, which demonstrates the validity of the method. The variation of the stress concentration factor with respect to plate thickness, hole size, distance between holes is presented in graphical form and discussed.

Influence of support friction on three-point bend test

One of the most commonly used tests for the experimental determination of the stress intensity factor is the so-called three-point bend test which has been adopted as a standard test by the American Society for Testing and Materials. It has been verified that the actual boundary conditions, i.e. support friction, play an important role in the stress intensity factor in the three-point bend specimen. In this paper the stress intensity factor considering friction at the supports is determined by a novel procedure, which may be of interest to researchers working on the numerical evaluation of stress concentration factors.