In order to solve fretting instability problem of gear shaft shoulder due to torsional vibration in mechanical system, the mathematical model of fretting instability vibration of gear shaft shoulder was established by...In order to solve fretting instability problem of gear shaft shoulder due to torsional vibration in mechanical system, the mathematical model of fretting instability vibration of gear shaft shoulder was established by adopting the method of combining kinematics and tribology, and the numerical analysis was applied to the fretting instability mechanism of gear shaft shoulder by introducing the friction instability damping ratio. The numerical results show that the main factors causing the unstable and vibrating gear shaft shoulder are the large tightening torque and too large static friction coefficient. The reasonable values of the static friction coefficient, the amount of interference and tightening torque can effectively mitigate the fretting instability phenomenon of gear shaft shoulder. The experimental results verify that damping plays a significant role in eliminating the vibration of gear shaft control system.展开更多
Lots of factors have influence on the firing accuracy of automatic weapon. During firing,the movement state of gun-shoulder system can be varied due to the impulsion of powder gases and the impact of moving parts,resu...Lots of factors have influence on the firing accuracy of automatic weapon. During firing,the movement state of gun-shoulder system can be varied due to the impulsion of powder gases and the impact of moving parts,resulting in a gunpoint being deviated from initial value to decrease the firing accuracy of weapon. The development of intelligent controlling gun carriage for weapon system is necessary for reflect its automatic firing accuracy objectively. An electronic measuring system for measuring the receiving force and movement of gun-shoulder system under initiative state is built based on the characteristics of standing non-rest automatic weapon. The constitutes of measuring system and the correction method of shoulder receiving force are described,and the mechanical admittance function of gun-shoulder system is obtained using electronically measured data,the modal identification of admittance functions of gun-shoulder system is made by adopting the orthogonal component method,and the key difference between the passive state and initiative state of standing non-rest automatic weapon is discussed.展开更多
目的探讨关节镜治疗中小肩袖撕裂(撕裂长度≤3 cm)合并肩关节粘连的中期疗效与不合并肩关节粘连的差距。方法回顾性分析我科2018年1月~2023年1月关节镜治疗中小肩袖撕裂且随访1年以上254例的临床资料,其中86例合并肩关节粘连,168例不合...目的探讨关节镜治疗中小肩袖撕裂(撕裂长度≤3 cm)合并肩关节粘连的中期疗效与不合并肩关节粘连的差距。方法回顾性分析我科2018年1月~2023年1月关节镜治疗中小肩袖撕裂且随访1年以上254例的临床资料,其中86例合并肩关节粘连,168例不合并肩关节粘连,通过倾向性评分匹配得到81对数据。比较2组末次随访肩关节疼痛和功能评分,包括疼痛视觉模拟评分(Visual Analogue Scale,VAS)、美国肩肘外科协会(American Shoulder and Elbow Surgeons,ASES)评分、Constant-Murley评分、美国加州大学洛杉矶分校(the University of California at Los Angeles,UCLA)肩关节评分;采用肩关节活动范围以及MR的Sugaya分级评估肩袖愈合情况和再撕裂率。结果合并肩关节粘连组与不合并肩关节粘连组随访时间分别为(42.2±13.0)月、(44.7±14.2)月(P=0.248)。合并肩关节粘连组术前VAS评分、ASES评分、Constant-Murley评分及UCLA评分均差于不合并肩关节粘连组(P<0.01),末次随访2组VAS评分、ASES评分、Constant-Murley评分及UCLA评分均较术前明显改善(P<0.001),2组间差异无显著性(P>0.05)。合并肩关节粘连组术前肩关节前屈、外展、体侧内旋和体侧外旋角度均小于不合并肩关节粘连组(P<0.001),末次随访2组肩关节4个活动度均较术前明显增大(P<0.01),合并肩关节粘连组仍差于不合并肩关节粘连组(P<0.05)。2组均无肩袖再撕裂(SugayaⅣ型和Ⅴ型),合并肩关节粘连组末次随访SugayaⅠ型占比少于不合并肩关节粘连组[21.0%(17/81)vs.60.5%(49/81),P<0.001]。结论中小肩袖撕裂合并肩关节粘连患者行关节镜下肩袖修复和关节囊松解手术可减轻肩关节疼痛,中期随访肩关节功能评分与不合并肩关节粘连者相近,肩关节活动度虽较术前明显改善,但仍不能达到不合并肩关节粘连者的水平。展开更多
基金Project(2008AA11A116)supported by the National High Technology Research and Development Program of ChinaProject(9140A2011QT4801)supported by advanced research of the Weapon Equipment Key Fund Program,ChinaProject(61075002)supported by the Independent Subject of State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body of Hunan University,China
文摘In order to solve fretting instability problem of gear shaft shoulder due to torsional vibration in mechanical system, the mathematical model of fretting instability vibration of gear shaft shoulder was established by adopting the method of combining kinematics and tribology, and the numerical analysis was applied to the fretting instability mechanism of gear shaft shoulder by introducing the friction instability damping ratio. The numerical results show that the main factors causing the unstable and vibrating gear shaft shoulder are the large tightening torque and too large static friction coefficient. The reasonable values of the static friction coefficient, the amount of interference and tightening torque can effectively mitigate the fretting instability phenomenon of gear shaft shoulder. The experimental results verify that damping plays a significant role in eliminating the vibration of gear shaft control system.
文摘Lots of factors have influence on the firing accuracy of automatic weapon. During firing,the movement state of gun-shoulder system can be varied due to the impulsion of powder gases and the impact of moving parts,resulting in a gunpoint being deviated from initial value to decrease the firing accuracy of weapon. The development of intelligent controlling gun carriage for weapon system is necessary for reflect its automatic firing accuracy objectively. An electronic measuring system for measuring the receiving force and movement of gun-shoulder system under initiative state is built based on the characteristics of standing non-rest automatic weapon. The constitutes of measuring system and the correction method of shoulder receiving force are described,and the mechanical admittance function of gun-shoulder system is obtained using electronically measured data,the modal identification of admittance functions of gun-shoulder system is made by adopting the orthogonal component method,and the key difference between the passive state and initiative state of standing non-rest automatic weapon is discussed.
文摘目的探讨关节镜治疗中小肩袖撕裂(撕裂长度≤3 cm)合并肩关节粘连的中期疗效与不合并肩关节粘连的差距。方法回顾性分析我科2018年1月~2023年1月关节镜治疗中小肩袖撕裂且随访1年以上254例的临床资料,其中86例合并肩关节粘连,168例不合并肩关节粘连,通过倾向性评分匹配得到81对数据。比较2组末次随访肩关节疼痛和功能评分,包括疼痛视觉模拟评分(Visual Analogue Scale,VAS)、美国肩肘外科协会(American Shoulder and Elbow Surgeons,ASES)评分、Constant-Murley评分、美国加州大学洛杉矶分校(the University of California at Los Angeles,UCLA)肩关节评分;采用肩关节活动范围以及MR的Sugaya分级评估肩袖愈合情况和再撕裂率。结果合并肩关节粘连组与不合并肩关节粘连组随访时间分别为(42.2±13.0)月、(44.7±14.2)月(P=0.248)。合并肩关节粘连组术前VAS评分、ASES评分、Constant-Murley评分及UCLA评分均差于不合并肩关节粘连组(P<0.01),末次随访2组VAS评分、ASES评分、Constant-Murley评分及UCLA评分均较术前明显改善(P<0.001),2组间差异无显著性(P>0.05)。合并肩关节粘连组术前肩关节前屈、外展、体侧内旋和体侧外旋角度均小于不合并肩关节粘连组(P<0.001),末次随访2组肩关节4个活动度均较术前明显增大(P<0.01),合并肩关节粘连组仍差于不合并肩关节粘连组(P<0.05)。2组均无肩袖再撕裂(SugayaⅣ型和Ⅴ型),合并肩关节粘连组末次随访SugayaⅠ型占比少于不合并肩关节粘连组[21.0%(17/81)vs.60.5%(49/81),P<0.001]。结论中小肩袖撕裂合并肩关节粘连患者行关节镜下肩袖修复和关节囊松解手术可减轻肩关节疼痛,中期随访肩关节功能评分与不合并肩关节粘连者相近,肩关节活动度虽较术前明显改善,但仍不能达到不合并肩关节粘连者的水平。
