Papers by Author: Ming Fa Ren

Abstract: In a curing process, there is an intensive residual stress in a cylinder with a reinforced part wrapped by hybrid composite due to the kinds of fibers and mismatch material properties. The development of residual stress in the cylinder is investigated by a finite element model combing with the classical laminate theory and heat conduction. The level of residual stress at the ends of reinforced part is higher than else location, a cure cycle with a lower cure temperature would reduce the residual stress. An improved cure cycle is proposed by comparing the simulational results of the cylinder cured with different cure cycle.

Abstract: This article demonstrates the buckling behavior of an advanced grid stiffened (AGS) composite plate under an axial loading. The experimental results acquired by a fringe projection profilometry system shows that the buckling of the AGS plate would gradually evolved from a local skin buckling to a global ribs buckling during the experiment. Kinds of failure mode would arise while the loading increasing, though an impressive peak loading was recorded before the AGS plate was crush. The whole-field deformation of the AGS plate during the experiment was retrieved by the fringe projection profilometry system.

Abstract: Lock-in infrared thermography method was gradually being used in fatigue studies because of its advantages such as real-time, quick-reaction, non-contact, non-destructive and so on. In this paper, non-destructive testing was applied to fatigue specimen with defects, based on lock-in infrared thermography. In parallel, the result was analyzed by using lock-in infrared thermography system developed by Cedip in French. The results show that more information of internal detects can be found from phase image than that from amplitude image. The experiment procedure indicated that a proper testing frequency was the key to the non-destructive testing. The data revealed that deeper depth and larger area of defect led to a precise testing result.

Abstract: This article demonstrates the co-curing process for AGS plate. Based on the phenomenological models of resin flow and cure kinetic, the variations of temperature, cure degree and pressure were illustrated during the process by a 2D FEA program. Some valuable results were obtained that the distribution of coupling fields could be more uniform with a proper cure cycle and mold, and the resin flow action would be completed in 6000s since the pressure was applied.

Abstract: In accordance with Helliger-Reissner variational principle, a semi-analytical Hamiltonian method has been developed for analyzing the process-induced stress analysis of composite wound vessel with metal liner during the curing process. A typical numerical result indicates that the process-induced thermo-stress fields involve complex variations of gradient and multi-peak values at different stages during the curing process.