A first order system model of fracture healing

INTRODUCTION Fracture healing is an important research subject in biomechanics. During the last years, many theories and simulation models have been proposed for de- veloping a comprehensive view of the mechanisms controlling bone morphogenesis. Pauwels (1960) was one of the first authors to propose a theory of tissue differentiation in response to local mechanical stress and strain. He assumed that deviatoric stresses com- prise the specific stimulus for the formation of fibrous connecti…     

脐血对骨折愈合影响的动物实验病理组织学及电镜观察

为证实脐血能否与骨髓一样有促进骨愈合的作用,72只新西兰兔随机被分为兔脐血、人脐血、对照及血肿组。病理组织学及电镜观察结果显示:血肿组较对照组愈合好,两脐血组间无明显差异,愈合质量均比血肿组好。结论:脐血与骨髓一样有促进骨折愈合作用。     

Distribution of Welding Residual Stress of Mixed Steel U-Rib-Stiffened Plates

To analyze the effects of width and thickness of each composition element of mixed steel U-rib-stiffened plates on the welding residual stress distribution, the distribution of the U-rib and the plate residual stress was calculated using a simplified calculation method. The method involved welding the mixed steel U-rib-stiffened plates for a structure with different sizes and different strength ratios of U-rib to plate. Based on a welding residual stress numerical simulation method validated by the blind hole method test, the distribution law of the mixed steel U-rib stiffened plate was studied. The results showed that the change of plate width has little impact on the welding residual stress and that the ratio of the thicknesses of the plate to U-rib stiffeners, the thickness of the plate, and the thickness of the U-rib has a great influence on the distribution of the welding residual stress. The thickness of plate and steel strength also greatly influenced the distribution width of the residual tensile stress. While analyzing the compression capacity of U-rib-stiffened plates, the simplified distribution of welding residual stress was used.     

钢梁与钢筋混凝土桥墩的新型刚节点联结形式及其静载反复试验

提出了一种新型的桥梁钢梁与钢筋混凝土桥墩的刚节点联结形式．刚节点内部构件间的连接全部采用高强度螺栓连接方式且施工方便，能够较理想地将上部结构弯矩传递到下部结构，剪力传递钢板承受了大部分的水平剪力．通过静荷载反复试验获得了有关这种新型结构性能方面的有效数据，试验结果表明该结构内部应力传递路径明确，并具有良好的抗震性能．有关结构的强度和塑性变形的计算及试验结果均表明，这种结构即使在发生很大变形的情况下，也能保持良好的能量吸收功能且没有出现因应力集中而发生的局部曲屈现象．由于避免使用了价格昂贵的支座，采用这种新型组合结构形式不但具有良好的抗震性能，同时可以降低桥梁的建设成本．     

高强度核电用钢厚板手工焊性能研究

介绍了武钢首批试制的高强度核电用钢厚板手工电弧焊性能研究,按照第三代核电技术(AP1000)用钢提出的焊接技术条件,对36mm和48mm两种规格的核电用厚钢板进行了手工焊焊接性能试验,研究结果表明:采用E9018-G-H4R核电专用焊条匹配WHD585E钢厚板所得焊接接头综合力学性能优良,能满足第三代核电用钢提出的焊接技术条件。     

Investigation of newly developed added damping and stiffness device with low yield strength steel

INTRODUCTIONThisresearchfocusedonusingthemechanicalpropertiesoflowyieldstrengthsteel(LYS)tode-velopanewdeviceforaddeddampingandstiffnessandseismicresistanceofrhombiclowyieldstrengthsteelplate.ThemechanicalpropertiesofLYSandtheeffectofthisnewlydevelopeddevicewereinvestigatedbyexperimentalmethod.Ex-pectedly,thisnewdevicecantakeadvantageofplasticenergyabsorbabilitytoabsorbanddissipatetheenergyofearthquakestablyandensurethesafetyofthemainstructure.Ananalyticalmodelisproposedforanalyzingtheh…     

Investigation of newly developed added damping and stiffness device with low yield strength steel

Energy dissipators, isolated-resistant and specific structural forms for earthquake resistance are popular topics in the research to improve shock-resistance. In this work, experimental methods were used to investigate the property of low yield strength steel. Carbon content in LYS material is lower than that in other steels; the ultimate stress is three times the yield stress. The ultimate elongation rate is about 62% and the ductility is 2–3 times that of A36 steel. In order to overcome some defects of ordinary use metallic dampers, the mechanical characteristic of low yield strength steel is used to develop added damping and stiffness for rhombic steel plate absorber. Test of the energy dissipation behavior for this newly developed device indicated that LYS could stably dissipate or absorb the input energy of earthquake. Then, the analytical model for the hysteretic behavior of this new device is proposed. Comparison of experimental data and numerical simulation results showed that this analytical model is suitable for simulating the hysteretic energy behavior of this new device.     

Lightweight design technology of planet carrier for wind turbine gearbox

A finite element model of one-arm planet carrier was built, and influence of structural parameters on strength and stiffness for one-arm planet carrier was analyzed. The stress and deformation of the round structure and the triangle structure for one-arm planet carrier were analyzed and compared. The finite element model of the same specifications arms planet carrier was established, and influence of the connecting slab thickness and input side plate thickness on strength and stiffness for arms planet carrier was analyzed. Strength, stiffness and mass for one-arm and arms planet carrier in the same specifications were analyzed and compared.     

软组织损伤对骨愈合中微循环影响的实验研究

目的:探讨软组织损伤对骨折愈合影响的作用机理。方法:作者选用新西兰大白兔32只,随机分成8组,均以右侧前肢为实验组,左侧为对照组。实验组骨折部位切除部分软组织。采用墨汁灌注血管的方法,观察骨折部位微循环变化。结果:实验组中骨皮质血供以髓内供应为主,而对照组以骨膜血供为主。实验组骨皮质萎缩变薄,骨皮质萎缩与骨膜微循环障碍有明显关系。结论:骨折愈合与局部微循环改变有明显关系,软组织损伤造成了骨折部位微循环障碍是骨折愈合延迟的主要作用环节。     

口内入路坚固内固定治疗下颌骨骨折132例的临床分析

目的：探讨口内入路坚固内固定治疗下颌骨骨折的临床效果。方法：对132例下颌骨骨折采取口内入路坚固内固定手术治疗的临床资料进行回顾性研究分析。结果：132例患者中127例（96．2％）患者伤口均Ⅰ期愈合,咬合关系恢复良好,骨折断端复位准确。结论：口内入路坚固内固定手术能安全有效地治疗下颌骨骨折,是一种值得推广的治疗方法。     

焊接冷裂纹临界冷却时间判据建立

用平板刚性拘束裂纹试验（ＰＲＲＣ）研究了４种国产低合金高强钢焊接冷裂敏感性，探讨了焊接接头扩散氢含量、焊接线能量、局部预热温度、拘束度的大小及局部预热产生附加应力等对钢材冷裂纹敏感性的影响。建立了国产低合金高强钢的临界冷却时间判据ｔｃｒ。实验表明此判据可靠，可用于评定现行焊接工艺条件下是否产生冷裂纹及确定合理的焊接工艺。     

Hierarchical models for failure analysis of plates bent by distributed and localized transverse loadings

The failure analysis of simply supported, isotropic, square plates is addressed. Attention focuses on minimum failure load amplitudes and failure locations, von Mises＇ equivalent stress along the plate thickness is also addressed. Several distributed and localized loading conditions are considered. Loads act on the top of the plate. Bi-sinusoidal and uniform loads are taken into account for distributed loadings, while stepwise constant centric and off-centric loadings are addressed in the case of localized loadings. Analysis is performed considering plates whose length-to-thickness ratio a/h can be as high as 100 （thin plates） and as low as 2 （very thick plates）. Results are obtained via several 2D plate models. Classical theories （CTs） and higher order models are applied. Those theories are based on polynomial approximation of the displacement field. Among the higher order theories （HOTs） HOTsa models account for the transverse shear deformations, while HOTs models account for both transverse shear and transverse normal deformations. LHOTs represent a local application of the higher order theories. A layerwise approach is thus assumed： by means of mathematical interfaces, the plate is considered to be made of several fictitious layers. The exact 3D solution is presented in order to determine the accuracy of the results obtained via the 2D models. In this way a hierarchy among the 2D theories is established. CTs provide highly accurate results for a/h greater than 10 in the case of distributed loadings and greater than 20 for localized loadings. Results obtained via HOTs are highly accurate in the case of very thick plates for bi-sinusoidal and centric loadings. In the case of uniform and off-centric loadings a high gradient is present in the neighborhood of the plate top. In those cases, LHOTs yield results that match the exact solution.     

南京地区610名公务员骨密度的年龄和性别特征分析

以南京地区610名公务员为研究对象,使用Sonost 2000超声骨密度仪测试受试者跟骨骨质状态的T值、Z值、骨强度指数、骨折风险等指标。结果显示:男、女性同性别40～50岁年龄组的骨密度状态指标中的T值、骨强度指数和骨折风险,与30～40岁年龄组均有显著差异(P<0.05或P<0.01),男性50～60岁年龄组的Z值的绝对值明显小于其他年龄组(P<0.01);同年龄组男、女性在各指标上均无显著性差异(P>0.05),男性各项骨密度指标值均优于同龄组女性。研究男、女性公务员骨密度的衰减明显期,可为其提高骨密度或防止骨密度衰减提供适宜的干预时机。     

磁刺激促进骨折愈合及对血液生化参数的影响(英文)

对１２０例新鲜骨折患者进行了磁刺激对骨折愈合和多种血液生化参数影响的试验研究,分析了磁刺激促进骨折愈合的作用机理．对比试验结果表明：磁刺激可促进钙盐沉着,加强人体的钙磷代谢,从而加速骨折的愈合过程．     

颈前路钢板螺钉内固定融合术治疗Hangman骨折

目的:探讨颈前入路C2-3椎体螺钉钢板内固定融合术治疗Hangman骨折的方法、临床效果和安全性.方法:9例Hangman骨折经颅骨牵引复位后,在仰卧位采取右侧颌下斜切口,在颈动脉鞘和内脏鞘之间进入椎前间隙,切除C2-3椎间盘,取自体髂骨移植,枢法模带锁钢板螺钉内固定.术后费城颈托外固定6～8周.术后所有患者随访6～30月,平均18个月.结果:本组9例病例均获得骨性融合,无假关节形成,颈部活动度正常,无神经功能受损症状.结论:经颈前入路C2-3椎体螺钉钢板内固定融合术治疗Hangman骨折可获得良好的即时稳定性,防止假关节形成和鹅颈畸形,有利于患者早期下床活动,且不影响颈椎活动度,是一种安全、效果良好的治疗方法.     

坚强内固定与颌间固定治疗下颌骨骨折87例临床分析

目的：探讨钛板坚强内固定与颌间固定治疗下颌骨骨折的临床效果。方法：87例下颌骨骨折患随机分为二组。一组采用上下颌牙弓夹板固定加颌间弹性牵引术(39例)．另一组采用钛板内固定加颌间弹性牵引术(48例)。治疗后对临床效果进行分析评价。结果：两组术后在感染发生率、骨愈合方面疗效基本相同。在咬合关系、张口度的恢复方面存在明显差异。结论：钛板坚强内固定治疗下颌骨骨折疗效满意，在咬合关系及张口度恢复方面优于颌间固定术。     

不锈钢接骨板和骨钉断裂失效分析

某医院植入患者体内的不锈钢接骨板和骨钉发生失效断裂。采用化学分析、断口和金相观察对该断裂失效的原因进行了分析。结果表明:00Cr18Ni15Mo3N接骨板孔洞边缘存在疏松孔隙和微裂纹是导致其断裂的主要原因;00Cr18Ni14Mo3骨钉断裂与其棱边小侧面存在的毛刺相关,同时其组织中异常存在的铁素体也加速了骨钉的断裂。     

平板—圆筒连接的应力数值分析及强度设计方法

本文主要对平板—圆筒连接结构计算模型进行了大量的应力数值分析,从中找出了圆平板在弹性支承下的应力分布规律。并首次采用(t/T)和(T/D)两个无量纲参数,提出了圆平板在弹性支承下的强度设计方法。从而较好地解决了飞机液压结构及着陆系统圆平板的强度计算;同时该设计方法,对压力容器平盖的强度计算亦具有指导意义。     

试论中国共产党政策制定的输入模式——新视角下的"从群众中来"

根据伊斯顿的政治系统理论,设若决策机制完善,那么输入就成为影响公共政策偏好的决定性因素。我国强势群体与弱势群体力量悬殊,决定中国共产党不能实行西方被动式的政策输入模式,放任二者进行利益博弈,而应坚持"从群众中来",深入群众,主动代表弱势群体利益,限制强势群体对政策的过大影响力,以获得自主性,使公共政策体现公共利益,并在此基础上改革现有政策输入机制,更好地实现"从群众中来"。     

不锈钢铝合金半固态连接工艺参数研究

By using semisolid joining technique,the bonding of stainless steel and semisolid aluminum alloy is successfully realized.The relationships between interracial shear strength and solid fraction of aluminum alloy,bonding pressure and time of keeping pressure were studied by the method of orthogonal experiment.The interfacial structure and the fracture structure of the bonding plate are studied by means of optical microscope (OM) and scanning electron microscope (SEM).The results show that there is the best solid fraction between the solid phase line and the liquid phase line of the semisolid aluminum alloy,with the increase of bonding pressure and pressure time,the interfacial shear strength increases rapidly,and then with further increase of bonding pressure and pressure time,the shear strength rises little.Along the interface,solid phase and liquid phase bond with stainless steel by turns because of the different diffusion ability.So,a new type of non-equilibrium diffusion interfacial structure is constructed at the interface of stainless steel and aluminum alloy,compound mechanism of plastic and brittle fracture interface was formed at the shear fracture interface.