With the development of the rail transit industry,more attention has been paid to the passive safety of rail vehicles.Structural damage is one of the main failure behaviors in a rail vehicle collision,but it has been ...With the development of the rail transit industry,more attention has been paid to the passive safety of rail vehicles.Structural damage is one of the main failure behaviors in a rail vehicle collision,but it has been paid little attention to in past research.In this paper,the quasi-static fracture experiments of SUS301L-MT under different stress states were carried out.The mechanical fracture properties of this material were studied,and the corresponding finite element simulation accuracy was improved to guide the design of vehicle crashworthiness.Through the tests,the fracture behavior of materials with wide stress triaxiality was obtained,and each specimen’s fracture locations and fracture strains were determined.Parameters of a generalized incremental stress state dependent damage model(GISSMO)of the material were calibrated,and the model’s accuracy was verified with test results from a 45°shear specimen.The GISSMO failure model accurately reflected the fracture characteristics of the material.The mesh dependency of this model was modified and discussed.The results show that the simulation agrees well with experimental data for the force-displacement curve after correction,but the strain distribution needs to be further studied and improved.展开更多
Objective: To better characterize nonunion endochondral bone healing and evaluate novel therapeutic approaches for critical size defect healing in clinically challenging bone repair, a segmental defect model of bone i...Objective: To better characterize nonunion endochondral bone healing and evaluate novel therapeutic approaches for critical size defect healing in clinically challenging bone repair, a segmental defect model of bone injury was adapted from the threepoint bending closed fracture technique in the murine femur.Methods: The mouse femur was surgically stabilized with an intramedullary threaded rod with plastic spacers and the defect adjusted to different sizes. Healing of the different defects was analyzed by radiology and histology to 8 weeks postsurgery. To determine whether this model was effective for evaluating the benefits of molecular therapy, BMP-2 was applied to the defect and healing then examined.Results: Intramedullary spacers were effective in maintaining the defect. Callus bone formation was initiated but was arrested at defect sizes of 2.5 mm and above, with no more progress in callus bone development evident to 8 weeks healing. Cartilage development in a critical size defect attenuated very early in healing without bone development, in contrast to the closed femur fracture healing, where callus cartilage was replaced by bone. BMP-2 therapy promoted osteogenesis of the resident cells of the defect, but there was no further callus development to indicate that healing to pre-surgery bone structure was successful.Conclusions: This segmental defect adaptation of the closed femur fracture model of murine bone repair severely impairs callus development and bone healing, reflecting a challenging bone injury. It is adjustable and can be compared to the closed fracture model to ascertain healing deficiencies and the efficacy of therapeutic approaches.展开更多
【目的】探讨经皮和开放经肌间隙椎弓根螺钉非融合固定治疗无神经功能障碍的A_(3)/A_(4)型胸腰椎骨折的临床疗效。【方法】采用前瞻性队列研究设计,选取2018年1月至2020年12月联勤保障部队第九〇〇医院收治的46例无神经功能障碍A_(3)/A_...【目的】探讨经皮和开放经肌间隙椎弓根螺钉非融合固定治疗无神经功能障碍的A_(3)/A_(4)型胸腰椎骨折的临床疗效。【方法】采用前瞻性队列研究设计,选取2018年1月至2020年12月联勤保障部队第九〇〇医院收治的46例无神经功能障碍A_(3)/A_(4)型胸腰椎骨折患者,将患者随机交替纳入经皮椎弓根螺钉固定(transmuscular space screwfixation,PPSF)组和切开经肌间隙椎弓根螺钉固定(Open transmuscular space pedicle screwfixation,OPSF)组。比较两组手术前后Cobb角、12个月后的矫正角丢失、失血量、手术时间、累积辐射时间。【结果】OPSF组和PPSF组手术前后Cobb角以及12个月后的矫正角丢失比较,差异无统计学意义(P>0.05)。与OPSF组比较,PPSF组手术时间更短,围术期失血量也更少,平均累积辐射时间更长,差异均有统计学意义(P<0.05)。【结论】经皮和切开经肌间隙椎弓根螺钉固定治疗无神经功能障碍A_(3)/A_(4)型胸腰椎骨折疗效相当,但经皮椎弓根螺钉固定手术时间更短,失血量也更少,但平均累积辐射时间更长。展开更多
基金National Natural Scienceof China(Grant No.52172409)Sichuan Provincial Outstanding Youth Fund of China(Grant No.2022JDJQ0025)。
文摘With the development of the rail transit industry,more attention has been paid to the passive safety of rail vehicles.Structural damage is one of the main failure behaviors in a rail vehicle collision,but it has been paid little attention to in past research.In this paper,the quasi-static fracture experiments of SUS301L-MT under different stress states were carried out.The mechanical fracture properties of this material were studied,and the corresponding finite element simulation accuracy was improved to guide the design of vehicle crashworthiness.Through the tests,the fracture behavior of materials with wide stress triaxiality was obtained,and each specimen’s fracture locations and fracture strains were determined.Parameters of a generalized incremental stress state dependent damage model(GISSMO)of the material were calibrated,and the model’s accuracy was verified with test results from a 45°shear specimen.The GISSMO failure model accurately reflected the fracture characteristics of the material.The mesh dependency of this model was modified and discussed.The results show that the simulation agrees well with experimental data for the force-displacement curve after correction,but the strain distribution needs to be further studied and improved.
基金Loma Linda Veterans Association for Research and EducationGrant/Award Number Seed Grant(to CR)+2 种基金US Department of Veterans AffairsGrant/Award Number Merit Review Award#5 I01 BX002519-04(to CR)Senior Research Career Scientist Award(to SM)。
文摘Objective: To better characterize nonunion endochondral bone healing and evaluate novel therapeutic approaches for critical size defect healing in clinically challenging bone repair, a segmental defect model of bone injury was adapted from the threepoint bending closed fracture technique in the murine femur.Methods: The mouse femur was surgically stabilized with an intramedullary threaded rod with plastic spacers and the defect adjusted to different sizes. Healing of the different defects was analyzed by radiology and histology to 8 weeks postsurgery. To determine whether this model was effective for evaluating the benefits of molecular therapy, BMP-2 was applied to the defect and healing then examined.Results: Intramedullary spacers were effective in maintaining the defect. Callus bone formation was initiated but was arrested at defect sizes of 2.5 mm and above, with no more progress in callus bone development evident to 8 weeks healing. Cartilage development in a critical size defect attenuated very early in healing without bone development, in contrast to the closed femur fracture healing, where callus cartilage was replaced by bone. BMP-2 therapy promoted osteogenesis of the resident cells of the defect, but there was no further callus development to indicate that healing to pre-surgery bone structure was successful.Conclusions: This segmental defect adaptation of the closed femur fracture model of murine bone repair severely impairs callus development and bone healing, reflecting a challenging bone injury. It is adjustable and can be compared to the closed fracture model to ascertain healing deficiencies and the efficacy of therapeutic approaches.
文摘【目的】探讨经皮和开放经肌间隙椎弓根螺钉非融合固定治疗无神经功能障碍的A_(3)/A_(4)型胸腰椎骨折的临床疗效。【方法】采用前瞻性队列研究设计,选取2018年1月至2020年12月联勤保障部队第九〇〇医院收治的46例无神经功能障碍A_(3)/A_(4)型胸腰椎骨折患者,将患者随机交替纳入经皮椎弓根螺钉固定(transmuscular space screwfixation,PPSF)组和切开经肌间隙椎弓根螺钉固定(Open transmuscular space pedicle screwfixation,OPSF)组。比较两组手术前后Cobb角、12个月后的矫正角丢失、失血量、手术时间、累积辐射时间。【结果】OPSF组和PPSF组手术前后Cobb角以及12个月后的矫正角丢失比较,差异无统计学意义(P>0.05)。与OPSF组比较,PPSF组手术时间更短,围术期失血量也更少,平均累积辐射时间更长,差异均有统计学意义(P<0.05)。【结论】经皮和切开经肌间隙椎弓根螺钉固定治疗无神经功能障碍A_(3)/A_(4)型胸腰椎骨折疗效相当,但经皮椎弓根螺钉固定手术时间更短,失血量也更少,但平均累积辐射时间更长。
