Reliability Research For Sintered Nano-silver Lap-shear Joint

Upon the experimental investigation on mechanical behaviors of sinterednanosilver lap-shear joint, the Anand constitutive model and a viscoplasticconstitutive model based on OW-AF nonlinear kinematic hardening were used topredict the uniaxial shear tests, cyclic shear ratcheting tests and mechanical fatiguelife tests of sintered nanosilver lap-shear joint. According to comparing with theexperimental results, the predicted results would be proved.A series of displacement-controlled uniaxial shear tests with different loadingrates and force-controlled cyclic shear ratcheting tests with different mean forces,force amplitudes, at peak force were conducted for sintered nanosilver lap-shear jointsat different temperatures. The relationship between force and displacement wasstudied. It was found that joints are highly rate-dependent and temperature-dependentand higher loading rate or lower temperature caused higher stress-strain response ofthe sintered nanosilver joint, and that the mean force, the force amplitude, and thedwell time played key roles in the shear ratcheting strain accumulation, especially inhigh temperature. In addition, according to the fatigue life tests with differentdisplacement amplitudes at room and high temperatures, it was found that and thetemperature have serious effects on fatigue life of sintered nanosilver lap-shear joint,and that along with rising temperature, the displacement amplitude has also effect onthe failure mode of the joint.The procedures and cautions of calling Anand model in ABAQUS andimplementing OW-AF model in UMAT would be emphasized in specialty. Aftercertificating the constitutive model by comparing with the reference, Anand modeland OW-AF model were used to simulate the shear tests, the ratcheting behavior andthe mechanical fatigue life of the sintered nanosilver joint. The comparison betweenexperimental data and predicted results by different models indicated that bothOW-AF model and Anand model agree well with uniaxial shear tests except severalinaccurate situations at high loading rate. In terms of simulating ratcheting behavior ofsintered nanosilver lap-shear joint, OW-AF model has a better capability to simulateratcheting behavior than Anand model, especially in the high temperature and longhold time in peak load situation. To be specific, at the325oC without hold time in peak load, the predicted data by OW-AF model is10.6%larger than experimental data,but the one by Anand model is204.7%larger than experimental data. When with5shold time at325oC, the deviation caused by OW-AF model is still small, but theresults predicted by Anand model is334%larger than experiment, which isunacceptable. When simulating the relationship between fatigue life and displacementamplitude, the prediction by OW-AF model also agrees well with the experiment, inwhich the error is not more than6%, but ones by Anand model are more than50%,even reaching70%.