Fracture in ductile materials often occurs in conjunction with plastic deformation.However,in the bond-based peridynamic(BB-PD)theory,the classic mechanical stress is not defined inherently.This makes it difficult to ...Fracture in ductile materials often occurs in conjunction with plastic deformation.However,in the bond-based peridynamic(BB-PD)theory,the classic mechanical stress is not defined inherently.This makes it difficult to describe plasticity directly using the classical plastic theory.To address the above issue,a unified bond-based peridynamics model was proposed as an effective tool to solve elastoplastic fracture problems.Compared to the existing models,the proposed model directly describes the elastoplastic theory at the bond level without the need for additional calculation means.The results obtained in the context of this model are shown to be consistent with FEM results in regard to force-displacement curves,displacement fields,stress fields,and plastic deformation regions.The model exhibits good capability of capturing crack propagation in ductile material failure problems.展开更多
The peridynamics(PD),as a promising nonlocal continuum mechanics theory,shines in solving discontinuous problems.Up to now,various numerical methods,such as the peridynamic mesh-free particlemethod(PD-MPM),peridynamic...The peridynamics(PD),as a promising nonlocal continuum mechanics theory,shines in solving discontinuous problems.Up to now,various numerical methods,such as the peridynamic mesh-free particlemethod(PD-MPM),peridynamic finite element method(PD-FEM),and peridynamic boundary element method(PD-BEM),have been proposed.PD-BEM,in particular,outperforms other methods by eliminating spurious boundary softening,efficiently handling infinite problems,and ensuring high computational accuracy.However,the existing PD-BEM is constructed exclusively for bond-based peridynamics(BBPD)with fixed Poisson’s ratio,limiting its applicability to crack propagation problems and scenarios involving infinite or semi-infinite problems.In this paper,we address these limitations by introducing the boundary element method(BEM)for ordinary state-based peridynamics(OSPD-BEM).Additionally,we present a crack propagationmodel embeddedwithin the framework ofOSPD-BEM to simulate crack propagations.To validate the effectiveness of OSPD-BEM,we conduct four numerical examples:deformation under uniaxial loading,crack initiation in a double-notched specimen,wedge-splitting test,and threepoint bending test.The results demonstrate the accuracy and efficiency of OSPD-BEM,highlighting its capability to successfully eliminate spurious boundary softening phenomena under varying Poisson’s ratios.Moreover,OSPDBEMsignificantly reduces computational time and exhibits greater consistencywith experimental results compared to PD-MPM.展开更多
目的探讨肉瘤样肾细胞癌组织中PD-L1的表达及肿瘤内微血管密度情况,为肉瘤样肾细胞癌免疫治疗及靶向治疗方案的选择提供理论依据。方法通过免疫组化法检测PD-L1、CD31及CD34在16例肉瘤样肾细胞癌(癌成分均为透明细胞肾细胞癌)中的表达,...目的探讨肉瘤样肾细胞癌组织中PD-L1的表达及肿瘤内微血管密度情况,为肉瘤样肾细胞癌免疫治疗及靶向治疗方案的选择提供理论依据。方法通过免疫组化法检测PD-L1、CD31及CD34在16例肉瘤样肾细胞癌(癌成分均为透明细胞肾细胞癌)中的表达,并评估肿瘤微血管密度。结果16例肿瘤中CD31和CD34免疫组化染色显示,肉瘤样肾细胞癌区域微血管密度明显高于不伴肉瘤样分化的区域,微血管密度计数分别为68.6±25.8 vs 38.7±16.0(t=3.931,P=0.0005)和69.5±28.1 vs 40.1±18.4(t=3.506,P=0.0015),差异有统计学意义。肉瘤样区域PD-L1表达水平高于非肉瘤样区域,CPS分别为34.7±26.9和25.9±27.6,但差异无统计学意义。结论在肉瘤样肾细胞癌中,肉瘤样区域微血管密度和PD-L1表达水平明显高于非肉瘤样区域,提示靶向治疗联合免疫治疗可能为此类肿瘤提供一种有效的治疗方法。展开更多
基金The corresponding author Lisheng Liu acknowledges the support from the National Natural Science Foundation of China(No.11972267)The corresponding author Xin Lai acknowledges the support from the National Natural Science Foundation of China(No.11802214).
文摘Fracture in ductile materials often occurs in conjunction with plastic deformation.However,in the bond-based peridynamic(BB-PD)theory,the classic mechanical stress is not defined inherently.This makes it difficult to describe plasticity directly using the classical plastic theory.To address the above issue,a unified bond-based peridynamics model was proposed as an effective tool to solve elastoplastic fracture problems.Compared to the existing models,the proposed model directly describes the elastoplastic theory at the bond level without the need for additional calculation means.The results obtained in the context of this model are shown to be consistent with FEM results in regard to force-displacement curves,displacement fields,stress fields,and plastic deformation regions.The model exhibits good capability of capturing crack propagation in ductile material failure problems.
基金supported by the National Key R&D Program of China(2020YFA0710500).
文摘The peridynamics(PD),as a promising nonlocal continuum mechanics theory,shines in solving discontinuous problems.Up to now,various numerical methods,such as the peridynamic mesh-free particlemethod(PD-MPM),peridynamic finite element method(PD-FEM),and peridynamic boundary element method(PD-BEM),have been proposed.PD-BEM,in particular,outperforms other methods by eliminating spurious boundary softening,efficiently handling infinite problems,and ensuring high computational accuracy.However,the existing PD-BEM is constructed exclusively for bond-based peridynamics(BBPD)with fixed Poisson’s ratio,limiting its applicability to crack propagation problems and scenarios involving infinite or semi-infinite problems.In this paper,we address these limitations by introducing the boundary element method(BEM)for ordinary state-based peridynamics(OSPD-BEM).Additionally,we present a crack propagationmodel embeddedwithin the framework ofOSPD-BEM to simulate crack propagations.To validate the effectiveness of OSPD-BEM,we conduct four numerical examples:deformation under uniaxial loading,crack initiation in a double-notched specimen,wedge-splitting test,and threepoint bending test.The results demonstrate the accuracy and efficiency of OSPD-BEM,highlighting its capability to successfully eliminate spurious boundary softening phenomena under varying Poisson’s ratios.Moreover,OSPDBEMsignificantly reduces computational time and exhibits greater consistencywith experimental results compared to PD-MPM.
文摘目的探讨肉瘤样肾细胞癌组织中PD-L1的表达及肿瘤内微血管密度情况,为肉瘤样肾细胞癌免疫治疗及靶向治疗方案的选择提供理论依据。方法通过免疫组化法检测PD-L1、CD31及CD34在16例肉瘤样肾细胞癌(癌成分均为透明细胞肾细胞癌)中的表达,并评估肿瘤微血管密度。结果16例肿瘤中CD31和CD34免疫组化染色显示,肉瘤样肾细胞癌区域微血管密度明显高于不伴肉瘤样分化的区域,微血管密度计数分别为68.6±25.8 vs 38.7±16.0(t=3.931,P=0.0005)和69.5±28.1 vs 40.1±18.4(t=3.506,P=0.0015),差异有统计学意义。肉瘤样区域PD-L1表达水平高于非肉瘤样区域,CPS分别为34.7±26.9和25.9±27.6,但差异无统计学意义。结论在肉瘤样肾细胞癌中,肉瘤样区域微血管密度和PD-L1表达水平明显高于非肉瘤样区域,提示靶向治疗联合免疫治疗可能为此类肿瘤提供一种有效的治疗方法。
