[Numerical study on the performance effect of the ratio of long axis to short axis of upright polypropylene infusion bag].

The study aims to investigate the effect of the ratio of long axis to short axis (RLS) of upright polypropylene infusion bag on discharging process and to search the best RLS. Aiming at five different RLS (1. 5 : 1, 2 : 1, 3 : 1, 4 : 1 and 5 : 1, respectively) with the volume of 100 mL, 250 mL and 500 mL, respectively, based on finite element method, analyzing the variation of stress distribution, emptying rate, drugging space and steadiness coefficient, etc. For the bags of the same volume, emptying rate increased with increasing of RLS, but the steadiness coefficient decreased with increasing of RLS. The specific increasing amplitude of emptying rate and decreasing range of steadiness coefficient were as follows: 20% and 49% for 100 mL infusion bag, 9% and 51% for 250 mL infusion bag, and 11% and 46% for 500 mL infusion bag, respectibvely, when RLS increased from 1. 5 : 1 to 5 : 1. Comparatively speaking, the increasing amplitude of the emptying rate is remarkably less than the decreasing range of the steadiness coefficient. By comprehensive consideration of both emptying rate and steadiness coefficient, lower RLS is recommended for upright polypropylene infusion bag.

[Numerical simulation of dental composite damage caused by water sorption].

Damage effects of water sorption on mechanical properties of the hydroxyapatite particle reinforced Bis-GMA/TEGDMA copolymer (HA/Bis-GMA/TEGDMA) have been predicted using 3-D finite cell models. Three different cell models were used to determine the influence of varying particle contents, interphase strength and moisture concentration on the debonding damage. The stress distribution pattern has been examined and the stress transfer mode has been clarified. The Young's modulus and fracture strength of the Bis-GMA/TEGDMA composite were also predicted using the model with and without consideration of the damage. The former results with consideration of the debonding damage are in good agreement with existing literature experimental data. The shielding effect of our proposed model and an alternative approach were discussed. The FCC cell model has also been extended to predict the critical load for the damaged and the undamaged composite subject to the 3-point flexural test.