The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform

Constanza Schapheer - One of the best experts on this subject based on the ideXlab platform.

Cristian A. Villagra - One of the best experts on this subject based on the ideXlab platform.

Song Huang - One of the best experts on this subject based on the ideXlab platform.

  • Effect of material defects on crack initiation under rolling contact fatigue in a bearing ring
    Tribology International, 2013
    Co-Authors: Song Deng, Song Huang
    Abstract:

    Abstract The effects of material defects such as pores on the crack initiation under rolling contact fatigue (RCF) in a bearing ring are investigated here. First, the main contact position between the ball and the raceway surface is investigated, and the effect of the depth of the pore on the crack initiation is analyzed. Second, several parameters, such as radial load, surface traction and raceway groove curvature radius (RGCR), are varied to evaluate stress intensity factors (SIFs), crack growth rates and crack growth angles. The results provide valuable guidelines for enhanced understanding of RCF in bearings.

  • Effect of material defects on crack initiation under rolling contact fatigue in a bearing ring
    Tribology International, 2013
    Co-Authors: Lin Hua, S.-E. Deng, Xinghui Han, Song Huang
    Abstract:

    The effects of material defects such as pores on the crack initiation under rolling contact fatigue (RCF) in a bearing ring are investigated here. First, the main contact position between the ball and the raceway surface is investigated, and the effect of the depth of the pore on the crack initiation is analyzed. Second, several parameters, such as radial load, surface traction and raceway groove curvature radius (RGCR), are varied to evaluate stress intensity factors (SIFs), crack growth rates and crack growth angles. The results provide valuable guidelines for enhanced understanding of RCF in bearings. ?? 2013 Elsevier Ltd.

Mohd Nasir Tamin - One of the best experts on this subject based on the ideXlab platform.

  • Damage Mechanics Model for Solder/Intermetallics Interface Fracture Process in Solder Joints
    Key Engineering Materials, 2011
    Co-Authors: Norhashimah M. Shaffiar, Mohd Nasir Tamin
    Abstract:

    The relatively brittle solder/IMC interface fracture process in reflowed solder joints is examined using finite element (FE) method. The interface decohesion is described using a traction-separation quadratic failure criterion along with a mixed-mode displacement formulation for the interface fracture event. Reflowed Sn-4Ag-0.5Cu (SAC405) solder ball on OSP copper pad and orthotropic FR4 substrate under ball shear push test condition at 3000 mm/sec is simulated. Unified inelastic strain constitutive model describes the strain rate-response of the SAC405 solder. Comparable simulated and measured load-displacement values during solder ball shear push test serve as validation of the damage-based FE model. Results indicate a nonlinear damage evolution at each material point of the solder/IMC interface during the ball shear push test. The normal-to-shear traction ratio at the onset of the interface fracture is 1.59 indicating significant induced bending effect due to shear tool clearance. Rapid interface crack propagation is predicted following crack initiation event with the average crack speed up to 24.6 times the applied shear tool speed. The high stress concentration along the edge of the solder/IMC interface facilitates local crack initiation and dictates the shape of the predicted dynamic crack front.

  • Damage mechanics of solder/IMC interface fracture in Pb-free solder interconnects
    2009 11th Electronics Packaging Technology Conference, 2009
    Co-Authors: Lai Zheng Bo, Loh Wei Keat, Mohd Nasir Tamin
    Abstract:

    This study addresses the mechanics of the relatively brittle solder/intermetallic (IMC) interface fracture process using damage mechanics concept. The damage state, ¿ of a material point in the solder/IMC interface, is expressed in terms of orthogonal traction components in a quadratic failure criterion of a cohesive zone model. The model is then employed in a finite element analysis of a solder ball shear push test. The simulated test specimen consists of reflowed SAC405 solder-on-OSP copper pad and orthotropic FR4 substrate. Unified inelastic strain constitutive model with optimized material parameters describes the strain rate-response of the SAC405 solder. The cohesive zone model parameter values are compiled from published experimental data on SAC405 solder ball pull tests and shear push tests. The predicted shear tool force-displacement curve compared well with published experimental data. The normal-to-shear traction ratio at the onset of interface fracture is 1.59 indicating significant induced bending effect due to shear tool clearance. Rapid interface crack propagation is predicted following the initiation of crack with the average crack speed up to 24.6 times the applied shear tool speed at 3000 mm/sec. The progressive boundary between damaged (¿

  • Damage Mechanics Model for Interface Fracture Process in Solder Interconnects
    2008 10th Electronics Packaging Technology Conference, 2008
    Co-Authors: Loh Wei Keat, Nazri Kamsah, Mohd Nasir Tamin
    Abstract:

    In this study, cohesive damage zone model is evaluated and employed to model solder/intermetallics (IMC) interface crack initiation and propagation in solder interconnects. Interface materials damage is quantified in terms of stress-to-strength ratios of orthogonal components in a quadratic failure criterion along with a mixed-mode displacement formulation for crack initiation event. Subsequent crack propagation is predicted based on fracture energy considerations. The mechanics of solder/IMC interface decohesion is examined through finite element modeling of a typical solder ball shear test. The 3D model consists of Sn40Pb solder, Ni3Sn4 intermetallics and Ni layers, copper substrate and a rigid shear tool. Unified inelastic strain theory describes the strain rate- and temperature-dependent response of the solder. The strength and work of fracture of the bi-material interface are derived from load-displacement data of solder ball pull tests and ball shear tests. The quasi-static solder ball shear test of reflowed solder sample is simulated at 30°C with a prescribed displacement rate of 0.01 mm/sec. Results show that complex stresses developed on the interface plane due to applied shear and induced bending effects by the shear tool clearance. A nonlinear damage evolution is predicted at each interface material point during the test. Stresses in the "fractured" material points diminish as the crack front progresses. The progression of damage indicates a straight crack front for the brittle solder/IMC interface fracture, as observed experimentally. The corresponding fractographic analysis on the sheared interface indicates that the crack initiated and propagated along the bi-material solder/IMC interface.

Prasanth Kumar Mallipudi L.dinesh - One of the best experts on this subject based on the ideXlab platform.

  • Study on Stress Analysis of Araldite HY-951 and CY-230 Bell Crank Lever using Photoelasticity and FEM
    Journal of Information Engineering and Applications, 2020
    Co-Authors: Prasanth Kumar Mallipudi L.dinesh
    Abstract:

    Bell crank lever is a bar capable of turning about a fixed point, used as a machine to lift the load by the application of small effort. Bell crank lever is used in railway signaling, governers of hartnell type, the drive for the air pump of condensers etc. The major stresses induced in the bell crank lever at the fulcrum are bending stress and fulcrum pin is shear stress. The maximum stresses are developed at the fulcrum. The Bell crank is a type of  crank that changes motion through an angle. The angle can be any angle from 0 to 360 degrees, but 90 degrees and 180 degrees are most common. Hence, the work deals with the stress analysis of bell crank lever within the angle ranges 90 0 to 180 0 by finite element method using ANSYS WORKBENCH 14.5 software and Photoelasticity. Experimental and Analytical results are observed and compared, so that the obtained results are in close agreement with each other. For the photoelastic stress analysis which is the Experimental method, the bell crank lever models are prepared with photoelastic sheet of Araldite hardener HY-951 and curing agent CY-230 is used. Keywords: Bell Crank Lever, Stress Analysis, MATLAB