The Experts below are selected from a list of 68160 Experts worldwide ranked by ideXlab platform
Mohsen Mohammadali - One of the best experts on this subject based on the ideXlab platform.
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A distributed Mechanical Joint contact model with slip/slap coupling effects
Mechanical Systems and Signal Processing, 2016Co-Authors: Hamid Ahmadian, Mohsen MohammadaliAbstract:Abstract This paper introduces a zero thickness interface model that considers hysteresis effects in both normal and shear directions of a contact. The model is rate independent and represents coupling effects between normal and shear displacements. Contact effects are included through a segment-to-segment contact model which considers stick, micro-slip, slide and slap behaviors at every point within the contact interface. The model has six parameters and three memory variables without the need for integration during response computations. Behavior of the model is validated using the available Mechanical Joint records in the literature and it is successfully employed for model identification and dynamic response prediction of an internally resonating test structure with frictional support.
Seung-boo Jung - One of the best experts on this subject based on the ideXlab platform.
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Correlation between the interfacial reaction and Mechanical Joint strength of the flip chip solder bump during isothermal aging
Journal of Materials Science: Materials in Electronics, 2005Co-Authors: Hyung-sun Jang, Seung-boo JungAbstract:The interfacial microstructure of Sn-37Pb solder with immersion Au/electroless Ni-P under bump metallization (UBM) was studied using scanning electron microscopy (SEM) and electron probe micro analyzer (EPMA). A Ni_3Sn_4 intermetallic compound (IMC) layer was formed at the interface between the solder and Ni-P UBM upon reflow. However, after thermal aging, AuSn_4 containing a certain amount of Ni dissolved in it, i.e. (Au,Ni)Sn_4, appeared above the Ni_3Sn_4 layer. The shear force of the Joints decreased with the aging period. The decrease of the shear force could be mainly caused by the coarsening effect of the microstructure within the solder, while the decrease after prolonged aging time should be due to the excessively grown IMC layer. A simple computational simulation was employed to interpret the failure mechanism of the shear tested specimens using finite element modeling (FEM). The FEM results explained well the ductile failure mode of the nearly whole tested Joints.
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effect of aging conditions on interfacial reaction and Mechanical Joint strength between sn 3 0ag 0 5cu solder and ni p ubm
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2005Co-Authors: Daegon Kim, Jongwoong Kim, Seung-boo JungAbstract:Abstract The interfacial microstructure of Sn–3.0Ag–0.5Cu solder with electroless Ni/immersion Au (ENIG) was studied using SEM, EPMA and TEM. (Cu,Ni)6Sn5 intermetallic compound layer was formed at the interface between the solder and Ni–P UBM upon reflow. However, after isothermal aging the AuSn4, with a certain amount of Ni dissolved in it, i.e. (Au,Ni)Sn4 appeared above the (Cu,Ni)6Sn5 layer. Two distinctive layers, P-rich and Ni–Sn–P, were additionally found from the TEM observation. The analytical studies using EDS in TEM revealed that the averaged composition of the P-rich layer is close to that of a mixture of Ni3P and Ni, while that of the Ni–Sn–P layer is analogous to the P-rich layer but containing a small amount of Sn in it. Shear force of the flip chip solder Joints decreased during aging at various temperatures. The decrease in shear force was mainly caused by the coarsening of microstructure within the solder and increase of the interfacial intermetallic compound thickness. Nearly all of the test specimens showed ductile failure mode and this could be well explained with the results of FEM analyses.
Brian R. Mace - One of the best experts on this subject based on the ideXlab platform.
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Modelling Uncertainty in Mechanical Joint Parameters using Component Modal and Fuzzy Approaches
III European Conference on Computational Mechanics, 2006Co-Authors: Jose Maria Campos Dos Santos, Brian R. MaceAbstract:Built-up structures consist of substructures connected through Mechanical Joints such as spot welds, rivets, bolts, etc., whose physical properties (stiffness, damping, thickness, etc.) can vary significantly from one structure to another. Uncertainties in these parameters generate uncertainties in the dynamic behaviour of the structure and there is an interest in predicting the variability of the response given the variability of the Joint parameters. In this paper, modelling and identification of a system consisting of two substructures connected by Mechanical Joints modelled by stiffness parameters is evaluated. Each substructure is modelled by a classical finite element method formulation and a modal solution obtained. The resulting modal solutions for the substructures are assembled in a Craig-Bampton component mode synthesis approach, which includes the Joint parameters. The stiffness properties of the Joints are described by fuzzy-valued parameters. Fuzzy-parameterized models are obtained using advanced fuzzy arithmetic based on the transformation method. Simulation results for this fuzzy model are obtained for different scenarios. Experimental results for a structure comprising two aluminum beams connected by steel wires are presented and compared with the simulated ones.
Tiantian Yang - One of the best experts on this subject based on the ideXlab platform.
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chemo Mechanical Joint detection with both dynamic and static microcantilevers for interhomologue molecular identification
Analytical Chemistry, 2012Co-Authors: Haitao Yu, Tiantian Yang, Ying Chen, Pengcheng Xu, Xinxin LiAbstract:The study presents a novel chemo-Mechanical Joint-sensing method to distinguish a certain molecule from its homologous chemicals, using both a resonant cantilever for gravimetric sensing and a static cantilever for surface-stress sensing. Homologous amines of trimethylamine (TMA, Me3N), dimethylamine (DMA, Me2NH), and monomethylamine (MMA, MeNH2) are herein used as model objects for investigation. The molecular identification is based on experimental characterizations on both molecule adsorbing capability (by the resonant cantilever) and intermolecular lateral interaction (by the static cantilever). The intensities of the two sets of sensing signals are expected to be in opposite sequence with each other, due to the complementary relationship among the interhomologue molecule structures, i.e., a molecule containing a greater number of methyl substituents must possess a fewer number of nonsubstituted hydrogens. On the basis of the proposed idea, ppm-level vapors of the three amines are sequentially detecte...
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Chemo-Mechanical Joint detection with both dynamic and static microcantilevers for interhomologue molecular identification.
Analytical chemistry, 2012Co-Authors: Tiantian Yang, Ying Chen, Dong-weon LeeAbstract:The study presents a novel chemo-Mechanical Joint-sensing method to distinguish a certain molecule from its homologous chemicals, using both a resonant cantilever for gravimetric sensing and a static cantilever for surface-stress sensing. Homologous amines of trimethylamine (TMA, Me(3)N), dimethylamine (DMA, Me(2)NH), and monomethylamine (MMA, MeNH(2)) are herein used as model objects for investigation. The molecular identification is based on experimental characterizations on both molecule adsorbing capability (by the resonant cantilever) and intermolecular lateral interaction (by the static cantilever). The intensities of the two sets of sensing signals are expected to be in opposite sequence with each other, due to the complementary relationship among the interhomologue molecule structures, i.e., a molecule containing a greater number of methyl substituents must possess a fewer number of nonsubstituted hydrogens. On the basis of the proposed idea, ppm-level vapors of the three amines are sequentially detected by a resonant microcantilever to characterize the molecular adsorption speed and another static cantilever to characterize the intermolecular lateral attraction induced surface stress. From the experiment, a pair of opposite sequence in sensing-signal amplitude has indeed been obtained that verifies the proposed Joint-sensing method. In addition, the two sensing signals both show a linear relationship with chemical concentration (at low-concentration range). Further comparison between the two sensing results can help to build a model to identify the molecule among a series of its homologous chemicals by eliminating the influence from concentration. Since a complementary relationship among homologous molecule structures widely exists, the dual-sensing method is promising in on-the-spot rapid molecular identification among homologous chemicals.
Dong-weon Lee - One of the best experts on this subject based on the ideXlab platform.
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Chemo-Mechanical Joint detection with both dynamic and static microcantilevers for interhomologue molecular identification.
Analytical chemistry, 2012Co-Authors: Tiantian Yang, Ying Chen, Dong-weon LeeAbstract:The study presents a novel chemo-Mechanical Joint-sensing method to distinguish a certain molecule from its homologous chemicals, using both a resonant cantilever for gravimetric sensing and a static cantilever for surface-stress sensing. Homologous amines of trimethylamine (TMA, Me(3)N), dimethylamine (DMA, Me(2)NH), and monomethylamine (MMA, MeNH(2)) are herein used as model objects for investigation. The molecular identification is based on experimental characterizations on both molecule adsorbing capability (by the resonant cantilever) and intermolecular lateral interaction (by the static cantilever). The intensities of the two sets of sensing signals are expected to be in opposite sequence with each other, due to the complementary relationship among the interhomologue molecule structures, i.e., a molecule containing a greater number of methyl substituents must possess a fewer number of nonsubstituted hydrogens. On the basis of the proposed idea, ppm-level vapors of the three amines are sequentially detected by a resonant microcantilever to characterize the molecular adsorption speed and another static cantilever to characterize the intermolecular lateral attraction induced surface stress. From the experiment, a pair of opposite sequence in sensing-signal amplitude has indeed been obtained that verifies the proposed Joint-sensing method. In addition, the two sensing signals both show a linear relationship with chemical concentration (at low-concentration range). Further comparison between the two sensing results can help to build a model to identify the molecule among a series of its homologous chemicals by eliminating the influence from concentration. Since a complementary relationship among homologous molecule structures widely exists, the dual-sensing method is promising in on-the-spot rapid molecular identification among homologous chemicals.