Papers by Keyword: Stress Concentration

Abstract: Fatigue test of the welded joint of 5083 aluminum alloy with smooth and height of specimen and the weld zone than the high test measurement and theoretical stress concentration coefficient calculation, the weld reinforcement effect of stress concentration on the fatigue performance of welded joints. The results show that: Smooth tensile strength of specimens for 264MPa, fatigue strength is 95MPa, the tensile strength of the 36%. Higher tensile strength of specimens for 320MPa, fatigue strength is 70MPa, the tensile strength of the 22%. Higher specimen stress concentration coefficient is 1.64, the stress concentration to the weld toe becomes fatigue initiation source, and reduces the fatigue strength and the fatigue life of welded joints.

Abstract: Most fatigue failures in aeronautical structures occur at fastened joints due to stress concentration (SC). Since more and more advanced composites are applied in aircrafts instead of conventional alloys, SC in CFRP composite plates with zigzag-arranged multiple holes has been investigated by finite element method in this paper. It is found that the static SC factor (SCF) of CFRP plates varies with the dimensionless bore and zigzag angle by a greater change than isotropic plates, and that the dynamic response amplitude and frequency of the SCF depend on the dimensionless bore and the dimensionless wave number related with material properties and the exciting frequency.

Abstract: This paper aims to experimentally study static responses of bridge longitudinal truss, and the distribution rules of the structural and local stresses were analyzed. The results of the analyses on experimental data show that the typical details in the longitudinal truss concentrate to a limited area on the toe of a dominate weld at the intersection among the upper chord or bottom chord, diagonal and the gusset plates; with boundary conditions being strengthened, stress distribution of the tested specimen became flat and the monolithic tress level decreased relatively. Based on obtained test information, the results are used for updating and validating this kind of structural model, and determining the parameters of finite element model.

Abstract: The study is based on wind power tower drum with Q345E low alloy steel weld detection of magnetic memory method, combining with the characteristic of X-ray photos of magnetic memory formation mechanism and made a detailed analysis. By doing this, it aims to show that increasing scan device on the number of channels, can to a certain extent, improve the accuracy of detection. Magnetic memory method is proved to be able to predict the nondestructive testing artifacts of the early damage and the possibility of micro crack germination to some extent. It shows that the weld seam can be quickly found dangerous parts by using the magnetic memory test full scan, coupled with the X-ray testing technology for defects, and it also can be further qualitative and quantitative and significantly improve the detection efficiency.

Abstract: Results for stress concentration in short members for isotropic plates with centered circular holes have been reported in the literature. More recently the influence of length for orthotropic holed plates has been examined and published as well. However, important aspects of stress considerations were missing such as the influence of load direction vs. material orientation which happens to have a strong influence on stress concentrations. Additionally, implied important misleading inaccuracies were reported. This analysis is meant to provide essential corrections to the published material.

Abstract: How to apply a torque is a very important problem in finite element analysis, and the traditional method utilizes a series of forces instead of the torque, but often leads in stress concentration. In this paper, many methods are being used to achieve the torque. And these methods are being compared, thus we can get several availability methods.

Abstract: One of the most widespread procedures used for building a shrink fit consists in a thermal process in which the hub is heated and lately cooled while the shaft is placed at the assembly final position, so the joint is radialy set. In this paper the contact pressure in a shrink fit is analyzed by means of the numerical simulations using FEA method. We compare the results with those obtained by the alternative building fit process, i.e., the axial press insertion, and, with the ones given by the pressure cylinders theory. Relevant information revealed from numerical simulations, as the stress and strain state after the assembly process, could be useful in the design of shrink fitted joints improving their performance during their life in service.

Abstract: The principle of roadway layout is in the low stress zone. Roadway will be difficult to support due to the lower seam face in the close multi-seam is affected by dynamic pressure of the upper seam face mining. The distribution of abutment pressure after the upper seam face mining were analyzed,concluded that: The layout of lower seam roadway should avoid the stress concentration area of residual coal pillar; Stress concentration of the coal pillar is related with mining order, and stress concentration degree is higher in the first mining side of the coal pillar; when the upper coal seam is gob, the layout of the roadway in the lower coal seam with the pattern of homodromous alternate interior layout will be easy to support.

Abstract: In order to determine stress concentration zones and defects on the surface of ferromagnetic components, the empirical model decomposition (EMD) method was proposed to eliminate noise interference of metal magnetic memory signal. Tensile-tensile fatigue test of 16MnR steel with prefabricated defects were carried out, and magnetic signals were measured using GMR sensor. The original metal magnetic memory signal was first decomposed into different intrinsic mode functions (IMF) and a residue, and reconstructed signal was obtained on the basis of the degree of the correlation coefficient. Results indicate that the reconstruction signal displays the maxima at 30mm, and there is a good correlation between the real maxima and the stress concentration zone. The EMD method is a effective signal processing method about magnetic memory signal containing some interference factors.

Abstract: A shaft of electric motor fin-fan cooler failed after two years operation. The inspection revealed that the v-belt attached on the electric motor loosed before the failure occurred. Visual investigation results showed the brittle fracture with less plastic deformation. Multiple crack origins observed on the edge of the shaft indicates that the more than one stress concentration generated within the shaft. Microstructure observation revealed fine grain on the edge and become coarse into the center of the shaft. The hardness test results were in good agreement to the microstructure observation where the edge are is harder than the center. Fractography using SEM revealed inclusions located within the shaft and some inclusions are clustered on the area where the cracks initiate to propagate. The presence of intermetallic inclusions was identified by microanalysis using EDS. Inclusions that are brittle in nature become stress concentrations for the operating load since its properties is close to ceramic. The presence of fine grain and inclusions on the edge of the shaft become detrimental to the shaft properties and the presence of fine grain aggravate the failure for its effect according to Hall-Petch theory.