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Torsional buckling and failure of carbon fiber/epoxy resin composite thin-walled tubes (CTWTs) were tested and analyzed, and the effects of torsional buckling on the material failure and failure loads were simulated by finite element method. In order to enhance the torsional bearing capacity of CTWTs, the buckling/failure of the tubes filled with polymer foam were further simulated by ABAQUS. Numerous...
According to the complicated working condition and heavy load properties of wind turbine transmission system, an analysis is performed considering bearing clearance and thermo-mechanical coupling. Taking a high-speed gear pair in a MW-class wind turbine transmission system as an example, the contact and bending of the gear pair are analyzed by using FEM (Finite Element Method). The analysis results...
Edge-to-edge repair (ETER) technique alters mitral valve inflow in the diastolic phase and thus the stress distribution on each leaflet, especially the area near sutured edges. In the present study, we performed finite element simulations of ETER mitral valve during the diastolic phase under different pressures. We conducted planar biaxial mechanical testing to obtain the material properties of native...
PoP is a potential solution to high-speed memory packaging. For PoP package, warpage is known as a concern over package stacking and SMT yield. The PoP package under current study has these features such as fine pitch which is 0.5 mm for both top and bottom, small ball size and that most solder balls are located at the packagepsilas two longer edges. Therefore the solder joint reliability (SJR) in...
A numerical modelling method for the analysis of solder joint damage and crack propagation has been described in this paper. The method is based on the disturbed state concept. Under cyclic thermal-mechanical loading conditions, the level of damage that occurs in solder joints is assumed to be a simple monotonic scalar function of the accumulated equivalent plastic strain. The increase of damage leads...
Thermomechanical reliability of the metal packaging with low-resistance and high-electric current was discussed in this paper. Thermal deformations and stresses of packaging structures were studied by both experimental and numerical methods. Laser speckle interferometry was used as the experimental method to test the coefficient of thermal expansion of the metal composite leads and the thermal deformations...
Board level drop testing is an effective method to characterize the solder joint reliability performance of miniature handheld products. In this study, some drop testing results were summarized based on our previous board-level drop tests. And then the finite element modeling and simulation were conducted to investigate and understand the drop reliability of lead-free solder joints by considering...
In this study, two types of global-local models are introduced. One is submodeling, in which a coarse global model is used to simulate the whole model and the fine local model is used to simulate the critical region of interest from whole model. The other is global-local-beam (GLB) model, in which the joint is replaced by an equivalent beam with effective stiffness. For submodeling, two different...
This paper describes a finite element parametric study of the reliability of the solder joints of a flip chip package in which the height H and diameter D of copper column interconnects are varied. It was found that when D was kept constant at 50 mum while H was varied, from 25 mum to 150 mum, there was a local optimum at around H=50 mum. Thus while the compliance of the interconnect with H=100 mum...
This paper focus on the study of solder constitutive model effect on solder joint fatigue life prediction. Two loading conditions are considered, namely thermal cycling and cyclic bending. In this study, four different solder constitutive models including elastic-plastic (EP), elastic-creep (Creep), elastic-plastic-creep (EPC) and viscoplastic Anand's (Anand) models are implemented in FE modeling...
This paper describes a finite element parametric study of the reliability of the solder joints of a flip chip package in which the height H and diameter D of copper column interconnects are varied. It was found that when D was kept constant at 50mum while H was varied, from 25mum to 150mum, there was a local optimum at around H=50mum. Thus while the compliance of the interconnect with H=100mum was...
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