Functional Outcomes of Adult Tibia Shaft Fractures Treated with Solid Intramedullary Nails versus Hollow Nails: A Systematic Review

Introduction: The management of fractures of the tibia shaft is an important aspect of orthopaedic care, and the selection of the surgical method for fixation can substantially impact patient outcomes. The current review aims to compare the outcomes of adult tibia fractures treated with solid nails to those treated with hollow nails. Methods: A search on Scopus, PubMed, and Cochrane Library, using three keywords (Outcome, Tibia shaft fractures, Nail) was conducted in April 2023. Results were compiled and two independent reviewers screened and selected eligible articles After removing duplicates, titles and abstracts were read to exclude ineligible studies. Full-text articles of the remaining papers were read to select eligible studies which were further critically appraised to ascertain their methodological quality. The data extracted from the selected papers were synthesized using a combination of pooling of results, tests of statistical difference (t-test and chi-square) and narrative synthesis methods. Results: A total of 2295 articles were obtained from the databases and citation searching. A total of 9 papers were identified as eligible and included in the review. Findings revealed that there is no statistical difference in the outcomes of tibia fractures treated with either solid or hollow nail groups such as duration of surgery (p = 0.541), rate of delayed and non-union (p = 0.342), and rate of surgical site infections (p = 0.395). Conclusion: Intramedullary nailing of tibia shaft fractures with either solid or hollow nails have similar functional outcomes.

Evolution of microstructure of aluminum alloy hollow shaft in cross wedge rolling without mandrel

During the process of cross wedge rolling of aluminum alloy hollow shaft, the evolution of its microstructure has an important influence on the mechanical properties of the rolled piece. In order to obtain the microstructure evolution law of aluminum alloy hollow shaft in cross wedge rolling without mandrel, a finite element model is constructed through the finite element software Deform-3D. The influences of rolling temperature, sectional shrinkage,spreading angle and forming angle on the average grain size of rolled piece are studied by numerical simulation of microstructure evolution. The cellular automata method reveals the inherent relationship between the process parameters and the evolution of the microstructure, and provides a reference for optimizing the rolling process parameters of aluminum alloy hollow shafts and improving the forming quality. The results show that the average grain size of the rolled piece increases with the increase of the rolling temperature, decreases with the increase of the sectional shrinkage,and decreases first and then increases with the increase of the spreading angle, and changes little with the increase of the forming angle.

Crack Fault Diagnosis and Location Method for a Dual-Disk Hollow Shaft Rotor System Based on the Radial Basis Function Network and Pattern Recognition Neural Network

The crack fault is one of the most common faults in the rotor system,and researchers have paid close attention to its fault diagnosis.However,most studies focus on discussing the dynamic response characteristics caused by the crack rather than estimating the crack depth and position based on the obtained vibration signals.In this paper,a novel crack fault diagnosis and location method for a dual-disk hollow shaft rotor system based on the Radial basis function(RBF)network and Pattern recognition neural network(PRNN)is presented.Firstly,a rotor system model with a breathing crack suitable for a short-thick hollow shaft rotor is established based on the finite element method,where the crack's periodic opening and closing pattern and different degrees of crack depth are considered.Then,the dynamic response is obtained by the harmonic balance method.By adjusting the crack parameters,the dynamic characteristics related to the crack depth and position are analyzed through the amplitude-frequency responses and waterfall plots.The analysis results show that the first critical speed,first subcritical speed,first critical speed amplitude,and super-harmonic resonance peak at the first subcritical speed can be utilized for the crack fault diagnosis.Based on this,the RBF network and PRNN are adopted to determine the depth and approximate location of the crack respectively by taking the above dynamic characteristics as input.Test results show that the proposed method has high fault diagnosis accuracy.This research proposes a crack detection method adequate for the hollow shaft rotor system,where the crack depth and position are both unknown.

Eigen value analysis of composite hollow shafts using modified EMBT formulation considering the shear deformation along the thickness direction

Composite hollow shafts are used in power transmission applications due to their high specific stiffness and high specific strength.The dynamic characteristics of these shafts are important for transmission applications.Dynamic modelling of these shafts is generally carried out using Equivalent Modulus Beam Theory(EMBT)and Layerwise Beam Theory(LBT)formulations.The EMBT formulation is modified by considering stacking sequence,shear normal coupling,bending twisting coupling and bending stretching coupling.It is observed that modified EMBT formulation is underestimating the shafts stiffness at lower length/mean diameter(l/dm)ratios.In the present work,a new formulation is developed by adding shear deformation along the thickness direction to the existing modified EMBT formulation.The variation of shear deformation along the thickness direction is found using different shear deformation theories,i.e.,first-order shear deformation theory(FSDBT),parabolic shear deformation theory(PSDBT),trigonometric shear deformation theory(TSDBT),and hyperbolic shear deformation theory(HSDBT).The analysis is performed at l/d_(m) ratios of 5,10,15,20,25,30,35,and 40 for carbon/epoxy composites,E-glass/epoxy composites,and boron/epoxy composite shafts.The results show that new formulation has improved the bending natural frequency of the composite shafts for l/d_(m)<15 in comparison with modified EMBT.The effect of new formulation is more significant for the second and third bending modes of natural frequencies.

Elastic and viscoelastic solutions to rotating functionally graded hollow and solid cylinders

Analytical solutions to rotating functionally graded hollow and solid long cylinders are developed. Young＇s modulus and material density of the cylinder are assumed to vary exponentially in the radial direction, and Poisson＇s ratio is assumed to be constant. A unified governing equation is derived from the equilibrium equations, compatibility equation, deformation theory of elasticity and the stress-strain relationship. The governing second-order differential equation is solved in terms of a hypergeometric function for the elastic deformation of rotating functionally graded cylinders. Dependence of stresses in the cylinder on the inhomogeneous parameters, geometry and boundary conditions is examined and discussed. The proposed solution is validated by comparing the results for rotating functionally graded hollow and solid cylinders with the results for rotating homogeneous isotropic cylinders. In addition, a viscoelastic solution to the rotating viscoelastic cylinder is presented, and dependence of stresses in hollow and solid cylinders on the time parameter is examined.

电力机车高强钢零部件焊修工艺技术研究

为了研究焊修次数对电力机车转向架关键零部件30CrMo合金钢空心轴组织及性能的影响,并优化其焊修工艺,对30CrMo合金钢空心轴行了三次焊修试验,并对每次焊修后的接头进行了静强度试验、金相试验和疲劳试验。静强度试验包括拉伸和弯曲试验,金相试验观察了接头各区域的显微组织,疲劳试验采用旋转弯曲加载方式,以确定接头的疲劳极限。结果表明:多次焊修后,接头的拉伸性能良好,拉伸试件断于母材;弯曲性能良好,弯曲角度达180°时无断裂或裂纹产生;室温和低温冲击性能在多次焊修后略有下降,符合标准要求;三次焊修焊缝硬度在330~340 HV之间,明显高于母材及热影响区硬度值。金相组织分析表明,空心轴母材的组织为回火索氏体、上贝氏体及块状铁素体,热影响区的主要组织为回火索氏体和少量块状铁素体,熔合区的组织为回火索氏体,焊缝组织为经过调质后产生的回火索氏体。接头疲劳极限满足强度要求,第三次焊修中值疲劳极限最高,在指定寿命为1×10^(7)次循环下的中值疲劳极限为399 MPa。焊后调质处理可以有效地改善多次焊修对接头性能的影响。多次焊修后的30CrMo合金钢空心轴接头具有良好的拉伸、弯曲和疲劳性能,且随着焊修次数的增加,接头的疲劳强度逐渐提高。该研究结果为电力机车转向架关键部件的焊修工艺优化提供了理论依据。

永磁无刷直流空心轴电机定子槽参数减振优化

为了保证永磁无刷直流空心轴电机的输出性能和抑制电磁振动,提出了一种基于非线性多元回归的修正代理模型优化方法.首先,通过AE(Audze-Elglajs)准则确定最优空间填充抽样,并采用核主成分分析(Kernel Principal Components Analysis,KPCA)算法筛选出4个主要变量用于构建代理模型;其次,采用非线性多元回归构建代理模型,决定系数R^(2)值均大于0.9,验证了代理模型的精度;最后,采用鲁棒多目标遗传算法求解代理模型,获得了最优定子槽参数.结果表明,通过优化定子槽参数,电机平均转矩降低了1.3%,不影响输出性能,电机空载、额定负载时最大振动加速度分别降低19%和34.5%,有效地降低了电磁振动,验证了优化方法的有效性和可靠性.

空心轴塑性成形技术应用进展及发展趋势

空心轴作为工业制造的核心组件之一,其高效、高精度成形对确保产品性能和提升生产效率至关重要。然而,传统自由锻和模锻在成形空心轴时存在材料利用率不高、成形精度不足及生产效率有限等问题,严重制约了空心轴的发展和应用。本文回顾了空心轴制造领域最新研究进展,剖析了当前存在的技术难题,并展望了新兴的成形技术及数字化、智能化技术在空心轴制造中的应用前景。总结了旋锻、挤压铸造、楔横轧和三辊斜轧等技术在提升空心轴制造效率与成形精度方面的应用和优势。旋锻通过旋转和锻造材料,有效提高材料利用率和产品性能;挤压铸造以高压将液态金属挤压入模具成形,实现了空心轴高精度成形和尺寸一致性;楔横轧通过模具带动坯料进行反向回转运动,金属同时发生径向压缩和轴向延伸变形,最终形成所需的阶梯轴类零件,提高了尺寸精度和生产效率;三辊斜轧技术则通过优化加载机制实现了局部加载下轴向高效连续塑性成形。未来,随着制造业向数字化和智能化方向发展,空心轴制造技术有望迎来更大的发展和突破。

径向开孔空心轴的扭转应力计算和结构改进

从满足工程应用实际需求出发,依据材料力学基本理论,推导出了开有多个径向孔的空心轴的极惯性矩和扭转应力的近似计算公式,利用推导公式进行了不同开孔方式下空心轴的扭转应力计算,确定了空心轴段径向开孔结构的改进方案,完成了工程应用中某驱动转轴断轴问题的技术改造。然后再利用ANSYS软件进行了模拟计算验算,ANSYS计算结果与近似公式计算结果偏差小于10%。近似计算公式对工程应用中径向开孔空心轴的扭转应力的近似计算和便捷设计校核具有参考意义。

薄壁四点接触球轴承-腕部关节系统接触动力学分析

在机器人实际工况中,针对含有薄壁四点接触球轴承的机器人腕部关节系统的运动稳定性问题,对腕部系统模型进行了简化设计和仿真研究。在考虑薄壁结构的弹性变形和动态接触作用耦合影响的基础上,建立了刚柔耦合工业机器人腕部关节系统模型,分析了不同受载工况和正反转驱动下的变形规律和动态特性。首先,基于多体动力学和Hertz接触理论,设计了包含薄壁四点接触球轴承和中空轴及基座的腕部关节系统刚柔耦合接触动力学仿真模型;然后,考虑薄壁中空轴、基座、轴承套圈和保持架的结构弹性变形、钢球和套圈滚道、保持架的动态接触作用,研究了机器人腕部关节系统两种实际工况对保持架和钢球角速度、保持架和薄壁基座振动位移、钢球与套圈的动态接触力的影响;最后,计算分析了两种工况下腕部关节系统的动态载荷规律和振动响应特性。研究结果表明:在相对较大的径向载荷作用下,保持架和钢球会出现打滑现象,速度呈现周期波动,保持架和基座具有更好的运动稳定性,其薄壁轴承内部载荷降低,主副接触对均承担联合载荷,轴承内部载荷稳定性也更好。该仿真模型及结果可以为薄壁腕部关节系统的动力学分析与设计提供参考。

轻量化多孔空心轴结构设计与分析

为了进一步提高轴的比强度,在传统空心轴的基础上进一步提出并研究了一种基于增材制造技术的多孔空心轴。通过仿真分析并经实验验证,在相同质量时,多孔空心轴与传统空心轴相比,承载能力更佳。在某典型扭转工况下,强度能提高22.5%;在某弯曲工况下,强度能提高9.8%。

新能源汽车空心电机轴径向锻造生产线设计

新能源汽车空心电机轴受力复杂,径向锻造是其最佳成形方式。本文分析了空心电机轴成形工艺流程,提出了生产线关键技术参数,介绍了关键设备组成,讨论了该生产线的技术特点。

7075铝合金传动轴空心轴身的挤压铸造工艺研究

采用挤压铸造工艺制备了7075高强铝合金传动空心轴缩比件,并对其轴身的组织性能进行了研究。结果表明,在浇注温度与模具温度分别为700℃与250℃条件下,随着挤压压力的增大,可逐渐获得结构致密、晶粒细小、力学性能优异的挤压铸造高强铝合金管坯,当压力为160MPa时,管坯的微观组织呈树枝状、颗粒状与蔷薇状相混合的结构形态,且其抗拉强度及伸长率均达到最大值,分别为545MPa与8%;断口分析发现,随着挤压压力的增大,7075铝合金经挤压后的断裂模式由解理断裂逐渐转变为塑性断裂。

空心轴类件楔横轧仿真及壁厚变化规律

基于Deform-3D软件,建立了平楔楔横轧成形空心轴类件三维刚-塑性大变形热应力耦合有限元模型。通过模拟仿真与实验数据对比,验证了该模型的正确性,并在此模型基础上,应用楔横轧各工艺参数的正交试验,分析了空心坯料的成形性及壁厚的变化规律。结果表明:所轧空心轴类件的壁厚对比度与成形角、展宽角成正比,与断面收缩率成反比。研究结果对轧制空心阶梯轴的应用以及准确预测空心轴类件壁厚的变化具有指导意义和实用价值。

全长锚固技术在深井软岩巷道中的应用

以顾北矿南翼6煤底板轨道大巷为全锚固试验巷道,在查阅大量相关文献的基础上,采用理论分析、数值模拟和现场试验相结合的综合研究方法,结合南翼6煤底板轨道大巷的实际情况,提出并成功实施了中空注浆锚杆、中空注浆锚索、矿用充填加固注射砂浆实现全长锚固注浆快速加固技术,替代了传统的采用重U型棚加固围岩工序,降低了工人的劳动强度,加快了巷道施工进度,并且安全高效、成本低廉、操作方便,取得了工业性试验成功。

楔横轧轧制空心轴类件损伤程度的研究

基于楔横轧轧制空心轴类件工艺,采用正交实验法对轧制过程中的工艺参数进行了有限元分析;引入Cockcroft&Latham损伤模型对空心轴类件在轧制过程中的损伤程度极其变化规律进行了研究,找出了影响空心轴类件轧制质量的主要工艺参数及规律,为实际生产提供了理论依据。

水平旋转内消能泄水道环流空腔直径的变化规律

本文从竖井进流水平旋转内消能泄水道影响环流空腔变化的因素出发,根据试验资料对其环流空腔直径的变化规律进行了系统地分析与研究。研究结果表明:这种泄水道环流空腔直径d0的变化规律有非常明确的分区特性,不同的分区对环流空腔直径d0影响因素是不同的。本文在该分析的基础上结合试验研究成果给出了d0的无因次综合变量函数的一般表达式、具体函数表达式和计算的经验公式。这些试验及分析成果对该种泄水道的水力特性的理论研究、分析计算和设计有较大的参考价值。

基于响应面法的转向驱动桥空心半轴轻量化优化设计

提出了一种基于数值优化与有限元模拟相结合的汽车转向驱动桥空心半轴轻量化设计方法。以半轴各段的壁厚、长度和过渡角为设计变量,半轴质量最小化为优化目标,2阶约束模态频率和半轴花键末端圆角过渡处等效应力为约束条件,建立了半轴轻量优化模型。利用正交试验设计得到10个设计变量和3个水平的数值模拟试验组合。采用最小二乘法建立了响应面近似模型,并利用序列二次规划算法对模型进行了迭代优化。结果表明:轻量化优化后的变径全空心半轴质量比初始设计减少约16.7g,半轴2阶约束模态频率增加约0.6Hz,且半轴花键末端圆角过渡处和最小轴径处的等效应力值均低于半轴材料的抗扭强度。

楔横轧轧制空心轴类件应变分析及其控制

基于Deform-3D软件,建立了楔横轧轧制空心轴类件三维刚—塑性有限元模型,研究了空心轴轧制过程中应变变化规律。研究结果表明,不同截面上有着不同的应变分布,并由不均匀的楔入段逐步过渡到较为均匀的展宽段直到基本均匀的自由段。在轴对称截面的外圆上轴向拉应变最大,内孔处径向压应变最大,并用径向应变对比度来反映该环形截面壁厚的变化趋势。通过增大该值,以提高轧坯抵抗缩颈的能力。

Al-5Ti-B及RE对挤压铸造7075铝合金传动空心轴组织和性能的影响

本文采用挤压铸造的方法制备了7075铝合金传动空心轴,研究了Al-5Ti-B及RE对挤压铸造7075铝合金铸件微观组织和力学性能的影响.结果表明:未加入细化剂的合金晶粒大小约为50μm,拉伸强度为454 MPa;加入0.29%RE的合金和1%A1-5Ti-B的合金,晶粒尺寸分别了减小到26μm和25μm,拉伸强度分别提高了16.3%和22.2%;同时加入0.29%RE和1%A1-5Ti-B对合金组织细化最为明显,晶粒尺寸减小到18μm,拉伸强度提高了26.6%,达到575MPa,延伸率为8.16%,布氏硬度为184.