This paper analyzes the stress of the printed circuit board (PCB) packaged by cushion materials after drop and investigates the stress of PCB under the different drop height, different cushion materials and different drop ground using ANSYS finite element software. The stress of PCB is analyzed quantitatively and qualitatively after drop, the results show: (1) The stress of the product is effected by drop height and the performance of dropping ground in a large extent; (2) The protect performance varies with the ways of cushioning packaging; (3) Within a certain range, the cushion material with smaller elastic modulus is better due to absorb the impact more energy and can bear the impact force is greater.

It’s very difficult to machine titanium alloy because of its features of small deformation coefficient, low thermal conductivity, small elastic modulus and large chemical activity. In this paper, we take titanium alloy TC4 as an example; using the finite element method (FEM) for the physical simulation of milling process, analyze the impact of some tool geometric parameters, such as rake angle, relief angle, rounded cutting edge radius etc., on chip form, cutting force, cutting temperature distribution of cutting tool and the maximum cutting temperature of rake face etc.. On this basis, we choose the best tool geometries, which can be taken as a theoretical reference for developing process plans of titanium alloy to reduce the number of tests and costs of field trials and to improve productivity.