薛斌 李星



【摘 要】復合材料跨尺度失效理論是近些年提出的一類基于物理失效模式的強度理論,它從細觀層面判定纖維和基體的失效,在分析復合材料性能匹配和耐久性方面有獨特的優勢。提出了一種新的跨尺度失效判定準則,利用Abaqus的內嵌Python腳本語言開發了復合材料跨尺度失效分析軟件CMFAS,編制了圖形用戶界面(GUI)進行人機交互,實現了代表體積單元(RVE)參數化建模及后處理、應力放大系數矩陣生成、失效準則臨界值求解和損傷演化處理等一系列功能,最終生成Abaqus子程序文件USDFLD和VUSDFLD。
【關鍵詞】復合材料;跨尺度;失效準則;二次開發
【Abstract】Composite multiscale failure theory is a newly proposed category of strength criteria, based on mechanical failure modes. In this theory, fiber and matrix failure are determined in meso level, which has special advantage in analyzing material property matching and durability. A new multiscale failure criteria was proposed, CMFAS (Composite Multiscale Failure Analysis Software) was developed using Python scripting language embedded in Abaqus. In CMFAS, GUI (Graphic User Interface) was compiled to realize human-computer interaction, RVE (Representative Volume Element) parametric modeling and post processing, stress amplification factors generation, failure criteria critical value solving and damage evolution were automatically accomplished, finally Abaqus subroutine files USDFLD and VUSDFLD were given.
【Key words】Composite materials; Multiscale; Failure criteria; Secondly development
0 引言
復合材料強度理論經過幾十年的發展,先后產生了Tsai-Wu準則[1]、Hashin準則[2]等幾十種失效判定方法,并且不斷有新理論的提出[3]。復合材料跨尺度失效理論是21世紀初發展起來的一類復合材料失效理論,通過宏觀應力(應變)計算細觀層面纖維和基體的應力(應變),基于物理失效模式判定纖維和基體的失效。在此基礎上可以討論纖維體積含量、溫度變化等對材料性能的影響,這是其它失效理論無法實現的[4-5]。因此跨尺度失效理論在研究復合材料纖維、基體性能匹配和耐久性方面有獨特的優勢,基于跨尺度失效理論的分析軟件也相繼提出。
1 跨尺度失效理論簡介
1.1 宏觀應力到細觀應力的轉換
復合材料纖維和基體的力學性能差異很大,它們在細觀上表現出不同的受力狀態。層板級力學試驗得到的應力是截面上纖維和基體的宏觀平均應力,并沒有反映細觀層面上的應力分布。假設纖維和基體按一定方式規則排列,可以認為施加在單層上的宏觀應力等效于施加在代表體積單元(RVE)上的應力,如圖1所示。
2 CMFAS的目的
應用跨尺度失效準則時,圖2中每個參考點都需求解式(1)中的機械應力放大系數矩陣和熱應力放大系數矩陣。當纖維或基體性能衰減后,應力放大系數矩陣又要重新計算。手工完成有限元計算和數據提取工作量很大,限制了跨尺度失效準則的實際應用,同時失效準則中臨界值的求解也需要編制程序來完成。CMFAS正是要為跨尺度失效準則的實際應用提供技術輔助,從人機交互和有限元求解兩個方面入手,為復合材料結構的跨尺度失效分析和損傷演化提供工具和手段。
3 CMFAS的功能和特點
3.1 CMFAS的功能
4.2 CMFAS的軟件編制和組成
(1)RVE參數化建模和后處理
(2)判定準則臨界值的求解
(3)損傷折減剛度求解及應力放大系數修正
(4)人機交互界面開發
5 結論
(1)復合材料跨尺度失效準則從細觀層面判定纖維和基體的失效,在研究復合材料纖維、基體性能匹配和耐久性方面有獨特的優勢。算例表明其可以有效預測復合材料的破壞過程;
(2)CMFAS可以有效實現復合材料跨尺度失效分析的整個過程,極大提高了計算效率,為跨尺度失效準則的實際應用提供了新的思路。
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[責任編輯:湯靜]