本文關鍵詞：基于Cocks-Ashby模型的多軸蠕變設計準則的局限性及其修正　出處：《機械工程學報》2017年16期 　論文類型：期刊論文

  更多相關文章： 黏塑性 多軸蠕變 Cocks-Ashby模型 簡化模型修正

【摘要】：多軸應力狀態(tài)下結(jié)構的蠕變變形分析是高溫裝備強度設計的理論基礎。經(jīng)典的Cocks-Ashby多軸蠕變孔洞長大模型及其簡化模型存在著嚴苛的適用條件及局限性,僅適用于描述高溫低應力環(huán)境下以晶間蠕變孔洞長大過程為材料蠕變損傷主要形式的蠕變變形行為。根據(jù)其簡化解得到的用于單-多軸蠕變延性換算的多軸蠕變因子則存在著在低三軸應力度段給出的計算值較試驗值偏小的問題。在基于WITCHMANN對該問題修正工作的基礎上,通過合理的進一步優(yōu)化,一個新的多軸蠕變因子被得出。將新修正因子應用在一個處于簡化恒定應力場中的發(fā)動機熱端葉片算例上,計算出恒載下葉片的等效多軸蠕變應變分布。有限元計算結(jié)果表明在葉片模型的葉根中部區(qū)域存在著較大的三軸應力度及較小的多軸蠕變因子,使得葉根中部原本應變不太明顯的區(qū)域也產(chǎn)生了較大的等效多軸蠕變應變,導致葉片計算出的潛在失效面積較未經(jīng)多軸蠕變因子修正前顯著增加。
[Abstract]:The multiaxial stress state of the structure under the creep deformation analysis is the theoretical basis for high temperature equipment and strength design. Multi axial creep cavity classic Cocks-Ashby growth model and its simplified model is suitable for harsh conditions and limitations, only suitable for describing the creep deformation behavior at high temperature and low stress intergranular creep void growth process mainly in the form of material creep the damage of environment. According to the simplified solution for the multi axial creep factor single - multiaxial creep ductility conversion exists should be calculated intensity values given by the experimental value than some small question in the low three axis. Based on WITCHMANN on the issue of the rectification work, through further optimized, a new multiaxial creep factor was obtained. The new correction factor used in a simplified constant stress field in the engine hot end blade example, calculated under dead load of blade etc. Effect of multi axial creep strain distribution. The finite element calculation results show that in the central region of the blade root blade model has three axis should be multi axial creep strength and smaller factors larger, makes the leaf root central strain less obvious areas had also produced a multi axial creep strain larger equivalent, resulting in potential failure leaf area calculation that is without the multiaxial creep factor correction increased significantly.

【作者單位】： 華東理工大學承壓系統(tǒng)與安全教育部重點實驗室;
【基金】：國家自然科學基金資助項目(51325504,51475167)
【分類號】：O344.6
【正文快照】： 0前言1蠕變是高溫設備中發(fā)生的一種依賴于溫度、載荷和服役時間的時效塑性變形行為,屬于黏塑性范疇。其產(chǎn)生機理和演化行為表現(xiàn)出強烈的溫度和載荷相關性,需要合理的模型和函數(shù)方程去描述。例如,在中等溫度和應力條件下,純金屬、合金等多晶體材料中發(fā)生的由位錯攀移導致的蠕變，

本文編號：1426799