Prediction for progression of transverse cracking in CFRP cross-ply laminates using Monte Carlo method

This study predicted transverse cracking progression in laminates including 90° plies. The refined stress field (RSF) model, which takes into account thermal residual strain for plies including transverse cracks is formulated, and the energy release rate associated with transverse cracking is calculated using this model. For comparison, the energy release rate based on the continuum damage mechanics (CDM) model is formulated. Next, transverse cracking progression in CFRP cross-ply laminates including 90° plies is predicted based on both stress and energy criteria using the Monte Carlo method. The results indicated that the RSF model and the CDM model proposed in this study can predict the experiment results for the relationship between transverse crack density and ply strain in 90° ply. The models presented in this paper can be applied to an arbitrary laminate including 90° plies

モンテカルロ法によるCFRP 直交積層板のトランスバースクラック進展解析

本論文では，90°層を含む積層板におけるトランスバースクラック挙動のモデル化を行った． トランスバースクラックを有する単層板の応力分布を熱残留ひずみの影響を考慮できるように拡張した応力分布 (RSF) モデルにより定式化し，定式化した応力分布によりトランスバースクラック発生に伴うエネルギー解放率を求めた． また，比較のために連続体損傷力学 (CDM) モデルによるエネルギー解放率の定式化も行った． その後，臨界応力およびエネルギー解放率に基づく応力クライテリオンおよびエネルギークライテリオンを設けてモンテカルロ法によるトランスバースクラック進展解析を実施し，CFRP直交積層板のトランスバースクラック挙動を調べた．その結果，本論文で提案したRSFモデルおよびCDMモデルは，実験値を良く表現できることが示された． 本論文で提案した解析モデルは90°層を含む積層板に対して適用が可能である．In this study, the prediction of the progression of transverse cracking in laminates, including 90° plies, was discussed. A refined stress field (RSF) model was formulated that takes into account the thermal residual strain for plies, including transverse cracks, and the energy release rate associated with transverse cracking was calculated using this RSF model. For comparison, the energy release rate based on a continuum damage mechanics (CDM) model was also formulated. Next, the prediction for the progression of transverse cracking in carbon fiber-reinforced plastic (CFRP) cross-ply laminates, including 90° plies, based on both stress and energy criteria was implemented using Monte Carlo methods. The results showed that the RSF and CDM models proposed in this paper can predict the experiment results for the relationship between the transverse crack density and ply strain in 90° plies. The models presented in this paper can potentially be applied to any arbitrary laminate that includes 90° plies

Continuum damage mechanics modeling of composite laminates including transverse cracks

In this study, the continuum damage mechanics model for predicting the stiffness re duction of composite laminates including transverse cracks is formulated as a function of crack density. To formulate the model, first the damage variable in the direction normal to the fiber of a ply including transverse cracks is derived. The damage vari able is derived by the model assuming a plane strain field in the isotropic plane and using the Gudmundson-Zang model for comparison. The effective compliance based on the strain equivalent principle proposed by Murakami and his colleagues and classical laminate theory are then used to formulate the elastic moduli of laminates of arbitrary lay-up configurations as a function of the damage variable. Finally, the results obtained from this model are compared to the finite element analysis (FEA) reported in previous studies. The model proposed in this paper can predict the stiffness of laminates containing damage due to transverse cracks (or surface crack) from just the mechanical properties of a ply and the lay-up configurations. Furthermore, this model can precisely predict the FEA results and experiment results for the elastic moduli of the laminate of arbitrary lay-up configuration, such as cross-ply, angle ply, and quasi-isotropic, includ ing transverse cracks. This model only considers the damage of the transverse crack; it does not consider damage such as delamination. However, this model seems to be effective in the early stage of damage formation when transverse cracking mainly oc curs. The model assuming plane strain field in the isotropic plane which is proposed in this paper can calculate the local stress distribution in a ply including transverse cracks as a function of crack density. The damage evolution of transverse cracks can thus be simulated by determining the fracture criterion