Extended finite element method （XFEM） implementation of the interaction integral methodology for evaluating the stress intensity factors （SIF） of the mixed-mode crack problem is presented. A discontinuous function...Extended finite element method （XFEM） implementation of the interaction integral methodology for evaluating the stress intensity factors （SIF） of the mixed-mode crack problem is presented. A discontinuous function and the near-tip asymptotic function are added to the classic finite element approximation to model the crack behavior. Two-state integral by the superposition of actual and auxiliary fields is derived to calculate the SIFs. Applications of the proposed technique to the inclined centre crack plate with inclined angle from 0° to 90° and slant edge crack plate with slant angle 45°, 67.5° and 90° are presented, and comparisons are made with closed form solutions. The results show that the proposed method is convenient, accurate and computationallv efficient.展开更多
为研究中心支板顶角对火箭基组合循环发动机(Rocket Based Combined Cycle,RBCC)进气道的影响,优化RBCC进气道设计方法,利用数值模拟对RBCC进气道开展了研究。分析了中心支板顶角变化对进气道内压缩段最小长度的影响,通过数值模拟对中...为研究中心支板顶角对火箭基组合循环发动机(Rocket Based Combined Cycle,RBCC)进气道的影响,优化RBCC进气道设计方法,利用数值模拟对RBCC进气道开展了研究。分析了中心支板顶角变化对进气道内压缩段最小长度的影响,通过数值模拟对中心支板顶角变化对典型工况下进气道的流场特征和性能影响开展了定量及定性的研究。研究结果表明,增加支板顶角可以减小进气道长度(相比于Strut_1,Strut_2至Strut_5的隔离段长度分别减少47%,62%,70%,75%)和粘性阻力系数(相比于Strut_1,在Ma∞=1.5时Strut_2至Strut_5内压缩段粘性阻力系数分别减少33%,45%,55%,59%;在Ma∞=5.5时Strut_2至Strut_5内压缩段粘性阻力系数分别减少37%,50%,57%和61%),但并不影响进气道流量系数和流动均匀度。同时根据研究结果对进气道进行优化设计,能有效提高进气道的起动能力及其他性能参数,进气道的内、外压缩段阻力系数分别降低13.5%和5.7%,总压恢复系数和循环静温比分别提高2.6%和0.5%。展开更多
基金Projects(41172244,41072224) supported by the National Natural Science Foundation of ChinaProject(2009GGJS-037) supported by the Foundation of Youths Key Teacher by the Henan Educational Committee,China
文摘Extended finite element method （XFEM） implementation of the interaction integral methodology for evaluating the stress intensity factors （SIF） of the mixed-mode crack problem is presented. A discontinuous function and the near-tip asymptotic function are added to the classic finite element approximation to model the crack behavior. Two-state integral by the superposition of actual and auxiliary fields is derived to calculate the SIFs. Applications of the proposed technique to the inclined centre crack plate with inclined angle from 0° to 90° and slant edge crack plate with slant angle 45°, 67.5° and 90° are presented, and comparisons are made with closed form solutions. The results show that the proposed method is convenient, accurate and computationallv efficient.
文摘为研究中心支板顶角对火箭基组合循环发动机(Rocket Based Combined Cycle,RBCC)进气道的影响,优化RBCC进气道设计方法,利用数值模拟对RBCC进气道开展了研究。分析了中心支板顶角变化对进气道内压缩段最小长度的影响,通过数值模拟对中心支板顶角变化对典型工况下进气道的流场特征和性能影响开展了定量及定性的研究。研究结果表明,增加支板顶角可以减小进气道长度(相比于Strut_1,Strut_2至Strut_5的隔离段长度分别减少47%,62%,70%,75%)和粘性阻力系数(相比于Strut_1,在Ma∞=1.5时Strut_2至Strut_5内压缩段粘性阻力系数分别减少33%,45%,55%,59%;在Ma∞=5.5时Strut_2至Strut_5内压缩段粘性阻力系数分别减少37%,50%,57%和61%),但并不影响进气道流量系数和流动均匀度。同时根据研究结果对进气道进行优化设计,能有效提高进气道的起动能力及其他性能参数,进气道的内、外压缩段阻力系数分别降低13.5%和5.7%,总压恢复系数和循环静温比分别提高2.6%和0.5%。
基金Supported by The National Natural Science Foundation of China(Grant No.51479153)the Fundamental Research Funds for the Central Universities(Grant No.2015-yb-004)
