Application of Failure Plastic Strain to Quasi-Static Finite Element Analysis for Projection Weld and Strain-based Spot Weld Evaluation

2011 ◽  
Author(s):  
Hwawon Lee ◽  
Parvath Police
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Strain ◽  
Spot Weld ◽  
Element Analysis

FINITE ELEMENT ANALYSIS OF CONSTRAINED GROOVE PRESSING OF PURE ALUMINUM SHEETS

2013 ◽  
Vol 02 (01) ◽  
pp. 1350001 ◽  
Author(s):  
S. S. SATHEESH KUMAR ◽  
I. BALASUNDAR ◽  
T. RAGHU
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Strain ◽  
Deformation Behavior ◽  
Strain Distribution ◽  
Pure Aluminum ◽  
Detailed Examination ◽  
Deformation Characteristics ◽  
Element Analysis ◽  
Aluminum Sheets

Constrained groove pressing (CGP) is an attractive severe plastic deformation technique capable of processing ultrafine grained/nanostructured sheet materials. The deformation behavior of pure aluminum during constrained groove pressing is investigated by carrying out a two-dimensional finite element analysis (FEA). FEA predicted deformation behavior observed during each stages of pressing indicated almost negligible deformation in flat regions, whereas the inclined shear regions revealed diverse deformation characteristics. The plastic strain distributions unveiled inhomogeneous strain distribution at the end of one pass. Detailed examination of plastic strain evolution during CGP along various sections divulged superior strain distribution along middle surfaces when compared to top and bottom surfaces. The degree of strain homogeneity is evaluated quantitatively along different regions of the sheet and is correlated to the deformation characteristics. Load–stroke characteristics obtained during corrugating and flattening of sheets exhibited three stages and two stages behavior, respectively. The results obtained from the analysis are experimentally validated by processing pure aluminum sheets by CGP and the measured deformation homogeneity is benchmarked with FEA results.

Design of BGA Assemblies with Enhanced Thermal Cycle Capability Using Solder Coated Polymer Balls

2016 ◽  
Vol 2016 (1) ◽  
pp. 000123-000133
Author(s):  
Thomas F. Marinis ◽  
Joseph W. Soucy
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Strain ◽  
Solder Ball ◽  
Cycling Performance ◽  
Temperature Cycling ◽  
Shear Load ◽  
Element Analysis ◽  
Solder Balls ◽  
Cycles To Failure

Abstract Solder coated polymer balls have been successfully employed for attaching packages to circuit boards with minimum standoff height, while accommodating large mismatches in thermal expansion coefficients. Dramatic improvements in temperature cycling performance are often realized by using them in place of solid solder balls, with five-fold increases in mean cycles to failure reported by a number of investigators. The sales literature, provided by suppliers of solder coated solder balls, attribute this superior temperature cycling performance to the soft, compliant polymer core of the product. Our study of the mechanics of solder coated polymer balls has revealed that their stiffness is in fact comparable to that of solid solder balls. Their rigidity results from a composite construction in which a nearly incompressible polymer material is surrounded by a copper shell that is not easily deformed from its spherical shape. We have employed finite element analysis and mechanical measurements to obtain load versus deflection curves for both normal compression and shear displacements of solder coated polymer ball connections. The enhanced temperature cycling performance of solder coated polymer ball connections is also derived from their composite construction. A cross-section through one reveals that near the solder pads, the ratio of copper to polymer is quite high, and consequently so is its resistance to shear. At the mid-plane of the connection, the ratio of copper to polymer is low, which minimizes its shear resistance. Thus, when a solder coated polymer ball connection is subjected to a shear load, as in temperature cycling, most of its deformation occurs around its mid-section. By contrast, when a solid solder ball is subjected to a shear load, most of its deformation occurs near its attachment pads, where its cross-sectional area and hence its stiffness are minimal. In either type of attachment, failure occurs when sufficient plastic strain damage accumulates in the solder to initiate a fracture. By distributing its shear strain over its midsection, a solder coated polymer ball minimizes plastic strain in its solder, where as a solder ball concentrates it near its bond pads. We have used finite element analysis to compute the cumulative plastic strain in various solder coated polymer ball assemblies subjected to cyclic shear loading induced by thermal excursions. By combining these results with an Engelmaier solder fatigue model, we predicted mean number of temperature cycles to failure of the solder connections. Our results compare favorably with published experimental data from temperature cycle tests. We have employed this analysis technique to examine how fatigue life is impacted by various connection parameters such as package size, stand-off height and solder composition, as well as those specific to solder coated polymer balls, which include size and mechanical properties of the core and ratios of solder and copper thicknesses to core diameter. Our overall objective is to enable design of complex stacked assemblies of multichip modules that meet customer reliability requirements for various use environments.

Finite Element Analysis of β-Titanium during Equal Channel Angular Extrusion

2011 ◽  
Vol 399-401 ◽  
pp. 1702-1707
Author(s):  
Jia Yong Si ◽  
Ze Hao Hu ◽  
Li Ping Zhong
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Strain ◽  
Strain Distribution ◽  
Equal Channel Angular Extrusion ◽  
Equivalent Plastic Strain ◽  
Element Analysis ◽  
Die Geometry ◽  
Plastic Strain Distribution ◽  
Angular Extrusion

The finite element analysis was applied to evaluate the respective influences of die geometry and process conditions on plastic strain distribution for β-titanium (Ti-13V11Cr3Al) during the equal channel angular extrusion. It was found that optimum ECAE die geometry is strongly material dependent. Optimal strain homogeneity in the Ti-13V11Cr3Al alloy may be achieved at r (inner radius) =5mm, R (outer radius) =3mm. The equivalent plastic strain increases with increasing friction coefficient. And the better homogeneity of the equivalent plastic strain distribution can be achieved when m=0.1. The faster is the ram speed, the lower is the homogeneity of the equivalent plastic strain distribution. The back-pressure can increase the strain level across the workpiece and prevent the problem of surface cracking induced by tensile stresses. The distribution of the plastic strain is not temperature sensitive between 400°C and 600°C.

FEA of reinforced concrete beam-column joint with steel fibers for cyclic loading

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shoaib Ahmad ◽  
Ghulamul Hasnain
Keyword(s):  
Finite Element Analysis ◽  
Experimental Study ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Cyclic Loading ◽  
Plastic Strain ◽  
Steel Fibers ◽  
Element Analysis ◽  
Content Type ◽  
Column Joint

PurposeSteel fibers reinforced concrete (SFRC) is now widely accepted as a construction material for its added benefits. The proven increases in high shear capacity, toughness, bridging action of fibers and bond improvement from addition of steel fibers into mix design is a field yet to be explored, Therefore, Reinforced Cement Concrete (RCC) beam-column joint with steel fibers was modeled and analyzed for cyclic loading.Design/methodology/approachBeam-column joint is the most critical section of a structure under mixed loading such as that during a seismic episode. Therefore, in this research a reinforced SFRC beam column joint is modeled and analyzed for cyclic earthquake loading with the help of finite element analysis (FEA) software ABAQUS to compare the results with the experimental study.FindingsNonlinear static and nonlinear dynamic analysis are carried out on the SFRC joint for the comparison of simulated results with the experimental analysis.Originality/valueIn this paper, Initially, modeling of SFRC joint was done. Then, the finite element analysis of beam-column joint with steel fibers was carried out. After number of simulations, obtained FEA results were compared with the experimental work on the based on the load vs deflection curve, shear stresses, plastic strain region and plastic strain pattern. After the comparison, it was found that the performance of the numeric model for cyclic loading verified the experimental study, and the results obtained were quite promising.

Study of a Plastic Strain Limit Damage Criterion for Pipeline Mechanical Damage Using FEA and Full-Scale Denting Tests

2016 ◽  
Author(s):  
Udayasankar Arumugam ◽  
Ming Gao ◽  
Ravi Krishnamurthy ◽  
Rick Wang ◽  
Richard Kania
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Strain ◽  
Critical Strain ◽  
Mechanical Damage ◽  
Ductile Failure ◽  
Full Scale ◽  
Element Analysis ◽  
Damage Indicator ◽  
Strain Limit

Pipeline constructed in rocky terrain is vulnerable to damages such as denting, gouging and other mechanical damages. In-line inspection (ILI) of these pipelines often reported several hundreds or even thousands of dents. Although most of these reported dents are well below 6% outside diameter (OD) depth limit as per ASME B31.8, few dents (sharp rock dents) with high strain could pose threat to integrity of the pipeline. Recently, strain-based models have been proposed to assess mechanical damage severity in pipelines. Attempts have also been made to characterize cracking susceptibility in rock dents using the critical strain based ductile failure damage indicator (DFDI) model. The objective of this study is to validate this model using full-scale denting tests conducted at the laboratory. Additionally, validation also extends to against the simplified DFDI model without finite element analysis (FEA). In this paper, the existing ASME strain limit and strain limit damage models are reviewed. The critical strain based strain damage model known as Ductile Failure Damage Indicator (DFDI) is then presented. The theoretical aspect of this model, including early work by Hancock and Mackenzie on strain limit (εf, reference failure strain) for ductile failure, is reviewed. The experimental aspect of material critical strain and its measurement using uni-axial tensile testing are then described. An elastic-plastic finite element analysis is employed to calculate DFDI, which is used to quantify the accumulated plastic strain damage and its susceptibility to cracking, and is validated using six full scale denting tests. Finally, the simplified strain limits for plain dent is proposed and validated.

CBGA Solder Joint Reliability Evaluation Based on Elastic-Plastic-Creep Analysis

2000 ◽  
Vol 122 (3) ◽  
pp. 255-261 ◽  
Author(s):  
John H. L. Pang ◽  
C. W. Seetoh ◽  
Z. P. Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Plastic Strain ◽  
Solder Joint ◽  
Thermal Cycling ◽  
Prediction Models ◽  
Nonlinear Finite Element Analysis ◽  
Nonlinear Finite Element ◽  
Element Analysis ◽  
Cycling Loading

Three-dimensional nonlinear finite element analysis of a ceramic ball grid array (CBGA) package was conducted to determine the solder joint creep and plastic strain deformations in a simulated thermal cycling loading. Two methods of analysis were carried out to model the creep deformations during the dwell and during the temperature ramps in the thermal cycling loading. The equivalent plastic and creep strains are presented for the two analysis method to demonstrate the differences in the strain components. Both creep and plastic strain fatigue life prediction models were used to estimate the thermal cycling life of CBGA solder joints subjected to accelerated thermal cycling tests. The lives predicted using this nonlinear finite element analysis results were satisfactory and conservative compared to the experimental test results. [S1043-7398(00)01103-8]

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