Study On Experimentation Of Moulded Pulp Pad And Its Imitation

The structure design of moulded pulp pad unit is the key point for its mechanics performance research, because the pad's protection relies on the distortion of its structure unit. While some big problems exist in both structure design and mechanic performance test so far away. One hand the structure design methodology in daily manufacture mainly adopts experience running short of modern technology and standard, leading to unreliable production. In order to guarantee the structure intension of pad, the suppliers will increase its thickness or make it much more complicated, followed by waste of pulp and increase of pulp cost. On the other hand, there are not any industrial or national mechanics performance standards for the test of moulded pulp pad, and serious errors would be brought on if the standards for plastic materials are used for moulded pulp pad. The two problems mentioned have been the choke point for the application and elevation of performance of moulded pulp pad, as well as the restriction for the production's popularization.This paper describes an efficient and logical finite element analyses method with CAE ANSYS to implement structure simulation for moulded pulp pad and imitation of static compression test.In order to imitate the structure unit of moulded pulp pad availably, the material parameter needed in the finite element analyses must be gotten from real test, and the analyses result must be compared and corrected by real static compression test result, to confirm the correction modulus between them. At the same time dynamic performance of pad are tested, including cushion performance under impact and librating transformation ratio.(1) Found the simulation parameters of moulded pulp material through draw experiments: tightening degree 5.7e-7 g/cm3 under 22～26℃and water contained 7.8～8.1%;Elastic modulus: 150MPa; Poisson ratio: 0.01. All of the parameters must be as basic material simulation data for the structure unit.(2) Static compression performance was tested to proof or correct the result of imitation. As normal distribution was found to be the static pressure distribution rule through statistics method, the expected value of swatch can be used to estimate the general performance. The whole pad's static compression performance which has a linear relation to the number of the pad can be counted by that of single unit.(3) The moulded pulp's cushion performance under impact was tested and the cushion curve is obviously different from other material, which is caused by different cushion mechanism. The conclusion is the efficient method to improve the cushion performance is to improve the structure intensity and optimize structure design.(4) Projected the librating transformation ratio test, and gained the resonance area of the tower shape moulded pulp pad is around 10Hz, and the biggest ratio is 1.370.(5) ANSYS was used to simulate the tower shape structure unit of the moulded pulp pad and imitate the real compression response process. Through analyzing the pressure-time and stress-time curves of six elements on typical position, the position where utmost pressure fastens is the center of the sides, and there the curves accord real test most. So we studied the relation between compression performance and the height of unit according to the pressure-displacement curves of the elements positioned near the center of sides. Imitated the units every 2.5mm from 7.5mm to 47.5mm height, and the conclusion is along with the increasing height the compression performance rises to apex until 27.5mm height and begins to fall down after that.