Abstract:

Based on the hexagon unit cell, the correlation matrices between the mechanical response fields of macro and micro structures are constructed, and an integrated macro/micro analysis method in composite cryogenic propellant tanks is established in this paper. With the commonly used engineering strength criteria capable of predicting the different damage modes, the matrix cracking in the composite laminate is predicted under the mechanical and temperature loads. Results show that the following criteria agree well with the test data under the mechanical loads, including the macroscopic Hashin criterion, modified macroscopic Tsai-Wu criterion, microscopic maximum stress criterion and microscopic Hashin criterion. However, considering the mismatching of the thermo-mechanical properties between the constituent materials, the predicted results using the microscopic strength criteria have imparities compared with the results using the macroscopic strength criteria under the thermal loads. Based on the comparison and analysis of the predicted results of the matrix cracking under different loads, the integrated macro/micro analysis method is proposed by utilizing the microscopic maximum stress criterion. Moreover, this method considers the effect of the imparities in the thermo-mechanical properties between the constituent materials, and is an effective way for the matrix cracking prediction of the composite tanks.

Key words: Composite tanks, Matrix cracking, Cryogenic, Unit cell, Strength criterion, Integrated Macro/Micro analysis method