A model based on the concept of the hypothetical fcp element is proposed to give the physical explanations to the existence of fcp threshold and why the fcp rate in near - threshold region coul 提出了近門檻區(qū)內(nèi)“裂紋擴展基元模型” ,用于定性地說明何以近門檻區(qū)內(nèi)裂紋擴展速率低于原子間距,進而解釋了裂紋擴展門檻值存在的物理本質(zhì)。
Test results and analysis show that the above equation can be applied to represent the fcp test results of various materials in the near - threshold region , the intermediate region of stable crack propagation and the rapid crack propagation region measured at different stress ratios 實驗結(jié)果和分析證明,該式能用于描述具有各種不同特性材料的包含近門檻區(qū)、中部穩(wěn)態(tài)擴展區(qū)和快速擴展區(qū)的整個疲勞裂紋擴展曲線。
Research on the expression of fcp rate had started more than 50 years ago . more than 100 formulas for fcp rate were developed ; among whom formulas describing the whole fcp curve , including the near - threshold region , the intermediate stable crack propagation region and the rapid crack propagation region , can be easily found 對疲勞裂紋擴展速率表達式的研究已有50余年的歷史,提出的裂紋擴展模型和表達式已達100多個;其中也有不少能描述包含近門檻區(qū)、中部穩(wěn)態(tài)擴展區(qū)和快速擴展區(qū)等三個區(qū)在內(nèi)的整個疲勞裂紋擴展曲線的表達式。
Main conclusions or / and creative work are given in following . all materials have same fcp pattern , i . e . , the whole fcp curve comprises the near - threshold region , the intermediate region of stable crack propagation and the rapid crack propagation region and with s shape , though the materials have different micro - mechanisms of fcp 本文的主要結(jié)論和創(chuàng)新點有:首先,認為所有固體材料均具有相同的疲勞裂紋擴展宏觀規(guī)律,即完整的疲勞裂紋擴展曲線都由近門檻區(qū)、中部穩(wěn)定擴展區(qū)和快速擴展區(qū)所構(gòu)成,曲線具有相似的s形,盡管不同特性的材料具有不同的疲勞裂紋擴展的微觀機制。
Based on the analysis and summation , a new formula for fcp is developed as eq . ( 3 . 23 ) or eq . ( 6 . 5 ) , and can be applied to describe the fcp pattern in all three fcp regions , including the fcp in the near - threshold region , the intermediate region of stable crack propagation and the rapid crack propagation region 在上述總結(jié)和分析的基礎(chǔ)上,給出了描述三個區(qū)的疲勞裂紋擴展總體規(guī)律的公式( 3 . 23 )或式( 6 . 5 ) ,即上述表達式左、右兩端量綱一致,式中的各個參量物理意義明確。