An improved procedure for manufacture of 3D tubes with springback concerned in flexible bending process

Three dimensional(3D)tubes,which possess the characteristics of space saving,lightweight and high strength,are widely used in many high-end industries such as aviation,aerospace,automobile and shipbuilding.However,when manufacturing a 3D tube in flexible bending process,springback is a big obstacle for improving the forming quality.In this paper,a new comprehensive strategy for springback control of 3D tubes is proposed.The strategy can be described as follows:(1)define the desired shape and manufacture shape;(2)optimize the manufacture shape using two tooling design methods(e.g.DA(displacement adjustment)method and B&T(bending and twisting)method presented in this paper);(3)make a discretization of the manufacture shape to acquire the optimized forming parameters.Additionally,experiment is implemented to validate the effectiveness of the new strategy.Results show that forming parameters acquired by the new strategy are partially effective.The new strategy also demonstrates that,during 3D tubes forming,the deviation caused by over-bent elements can be counteracted by the deficient-bent elements.This principle is helpful to reduce the difficulty of parameter determination in future.

Dynamic response of ultralight all-metallic sandwich panel with 3D tube cellular core to shallow-buried explosives

The underbody of a vehicle system, either military or civil, is typically made of a relatively thin metallic plate, thus vulnerable to mine blast attacks. To improve the blast resistance, a multitude of protective structures have been proposed as attachments to the thin plate. In the present study, a novel ultralight all-metallic sandwich panel with three-dimensional(3D) tube cellular cores mounted to the vehicle underbody was envisioned as such a protective system. A metallic substrate(mimicking vehicle bottom)was placed above the proposed sandwich panel to construct a sandwich-substrate combinative structure. A series of sandwich panels having 3D tube cellular cores were fabricated via argon protected welding and laser welding. Mechanical responses of the combinative structure subjected to the denotation of 6 kg TNT explosives shallow-buried in dry sand were experimentally measured. Full numerical simulations with the method of finite elements(FE) were subsequently carried out to explore the physical mechanisms underlying the observed dynamic performance and quantify the effects of key geometrical parameters and connection conditions of the protective system. The performance of the proposed sandwich panel under shallow-buried explosives was also compared with competing sandwich constructions having equal mass. Finally, a preliminary optimal design of the 3D tube cellular core was carried out.

Fin formation model during pre-roll ploughing of copper 3D outside fin tube

The mechanism of pre roll ploughing for 3D fins on the outside surface of copper tube was studied systematically, and especially the process and conditions of 3D fin formation were analyzed. The right mathematical model was also established. Based on the volume of fin ploughed out is equal to the volume of the metal extruded up by the extruding face of the tool, the relations between fin height, pre roll ploughing feed and pre roll ploughing depth have been achieved. With the increase of pre roll ploughing depth which must be equal to groove depth, the fin height gradually becomes larger. There are different critical feeds with the various depths of pre roll ploughing. The pre roll ploughing feed is the critical one, the height of fin is largest. And when the feed is above the critical one, the fin height will reduce with the increase of feed. The theoretical analysis basically accords with experimental results.

3D Grid of Carbon Tubes with Mn3O4-NPs/CNTs Filled in their Inner Cavity as Ultrahigh-Rate and Stable Lithium Anode

Transition metal oxides are regarded as promising candidates of anode for next-generation lithium-ion batteries(LIBs)due to their ultrahigh theoretical capacity and low cost,but are restricted by their low conductivity and large volume expansion during Li^(+)intercalation.Herein,we designed and constructed a structurally integrated 3D carbon tube(3D-CT)grid film with Mn_(3)O_(4)nanoparticles(Mn_(3)O_(4)-NPs)and carbon nanotubes(CNTs)filled in the inner cavity of CTs(denoted as Mn_(3)O_(4)-NPs/CNTs@3D-CT)as high-performance free-standing anode for LIBs.The Mn_(3)O_(4)-NPs/CNTs@3D-CT grid with Mn_(3)O_(4)-NPs filled in the inner cavity of 3D-CT not only afford sufficient space to overcome the damage caused by the volume expansion of Mn_(3)O_(4)-NPs during charge and discharge processes,but also achieves highly efficient channels for the fast transport of both electrons and Li+during cycling,thus offering outstanding electrochemical performance(865 mAh g^(-1)at 1 A g^(-1)after 300 cycles)and excellent rate capability(418 mAh g^(-1)at 4 A g^(-1))based on the total mass of electrode.The unique 3D-CT framework structure would open up a new route to the highly stable,high-capacity,and excellent cycle and high-rate performance free-standing electrodes for highperformance Li-ion storage.

A Study on 3D FE Simulation Method of NC Bending Process of Thin-walled Tube

The numerical control (NC) precision bending process of thin-walled tube is on e of advanced plastic forming processes with high efficiency, forming precision, strength/weight ratio and low cost, thus it is playing more and more important role in manufacturing parts in aerospace and automobile industries. However, the determination of parameters crucial to make sure tube parts qualified is heavil y experience-based and involves repeated trial-and-errors in practice, which makes the production efficiency reduce drastically and does not fulfill the deve lopment of high technology. With quick development of computer technology and gr adual perfect of plastic forming theory, computer numerical simulation based on finite element method (FEM) has become one of important tools of researching and developing plastic forming technology. Development trend of NC precision bendin g process of tube is simulating its forming process by FEM. Because NC tube bend ing is of 3D nature, it is of great importance to analyze the forming mechanism and find out the influence law of forming parameters on forming process in the N C precision bending process of thin-walled tube quantitatively by 3D FE simulat ion. Based on the rigid-plastic finite element method (FEM) principle, a 3-dimens ional (3D) rigid-plastic FE simulation system named TBS -3D (tube bending simu lation by 3D FEM) for the NC bending process of thin-walled tube has been devel oped, a reasonable FEM model has been established. By use of this FEM simulation system, a NC bending process of thin-walled has been simulated. And deformed m eshes under different bending stages, stress distribution along bending directio n, relationship between maximal wall thickness changing ratio and bending angle have been obtained. And then some forming laws of NC tube bending obtained are a s follows: (1) NC bending process make tube elongate to some extent; (2) Charact eristic of stress distribution is that the outer area is undergoing tensile stre ss, the inner area is undergoing compression stress, and stress neutral layer mo ves close to the inner area, which is in good accordance with the practice; (3) Maximal wall thinning ratio in the outer tensile area changes only a little with increase of bending angle, and maximal wall thickening ratio in the inner compr ession area increases linearly with bending angle. The above results show that 3 D FE simulation is an important and valid tool of analyzing NC bending process o f tube, this research is beneficial for the practical tube bending process, and it may serve as a significant guide to the practice of the relevant processes.

Effects of Microstructure on Quasi⁃Static Transverse Loading Behavior of 3D Circular Braided Composite Tubes

The effects of microstructure on quasi-static transverse loading behavior of 3D circular braided composite tubes were studied. Transverse loading tests were conducted. Transverse load-deflection curves were obtained to analyze the effects of braiding parameters including the braiding angle, the wall thickness, and the diameter on the transverse loading of 3D circular braided composite tubes. Breaking loads, moduli and strengths had also been used to describe the transverse loading behaviors. The failure morphologies were shown to reveal damage mechanisms. From the results, the increase in braiding angle, wall thickness and diameter increases the ability of anti-deformation and breaking load of braided tubes. The breaking load of specimen with a braiding angle of 45° is about 1.68 times that of specimen with a braiding angle of 15°. The breaking load of specimen with 4 layers of yarns is about 2.15 times that of specimen with 2 layers of yarns. The breaking load of the tube with a diameter of 25.5 mm is about 2.39 times that of the tube with a diameter of 20.5 mm.

双组份水凝胶3D打印静态混合管设计

针对双组分水凝胶梯度材料3D打印机的静态混合管进行了优化设计。通过建立模型,采用模块化的分析设计方法,对不同设计参数的分离混合型的静态混合管进行了定性与定量地仿真分析。最优的设计结合改装的Prusa i3结构的3D打印系统,打印不同比例的聚乙烯醇(PVA)/海藻酸钠(SA)双组份水凝胶结构。通过多个虚拟打印头,进行了PVA/SA的梯度打印,并通过阈值分割验证梯度效果。展示了双组分静态混合管的新设计以及其在生物兼容性梯度功能材料打印的应用。

CT球管参数设定对腰椎骨折3D打印模型影响的体模研究

目的:分析不同CT球管参数设定对腰椎骨折3D打印模型的影响,探讨适合腰椎骨折术前3D打印模型的低剂量CT扫描参数。方法:利用东芝640层CT对L1-L2椎体棘突骨折腰椎模型进行扫描,A、B两组的扫描管电压分别为120、100 kV,管电流均依次设定为160、140、120、100、80、60、40、20 mA。由两位高年资影像诊断主治医师对骨折线的可发现、可诊断和整体图像质量进行主观评价,另由两位高年资骨科主治医师对3D打印模型清晰度、手术指导情况进行主观评价,均采取3分评价法,评分≥2分为可接受。结果:两位医师对骨折线及3D打印模型的主观评价一致性均较好,各组3D打印模型评价均为3分。管电流为20 mA时,A、B两组L2棘突骨折线评分均为1分,图像质量差,其余骨折线评分均为2分或3分。不同参数L1-L5双侧椎弓根左右径宽度均值范围为9.42~10.19 mm,不同参数腰椎3D打印模型L2-L5双侧椎弓根上下径长度均值范围为12.15~12.52 mm,差异均无统计学意义(P值均>0.05)。A组管电流为20 mA,B组管电流为40 mA时,噪声最低,信噪比(SNR)、对比噪声比(CNR)最高,分别为11.7、15.31、95.72和8.62、30.97、165.10;随着辐射剂量降低,噪声降低,SNR、CNR升高。结论:采用低管电压、低管电流CT扫描能够满足3D打印模型的临床需求和腰椎骨折诊断需求。

3D激光雷达中激光编码器的驱动控制

目的是解决激光器出光稳定性问题,3D激光雷达系统通过计算激光的飞行时间(Time Of Flight,TOF)得到目标的距离信息,经过处理所获得的数据信息恢复出探测目标的三维图像。激光雷达系统常用的调Q激光器存在着出光抖动的问题,而激光器的出光选通抖动直接影响了成像效果,所以解决激光器出光稳定性问题成为了提高TOF激光雷达性能的主要目标之一。方法是通过设计一种新型外置出光选通控制器,由高精度电机控制编码器高速旋转产生光通断信号,光电对管(光遮断器)将激光器发出的光脉冲信号转换为TTL触发电频信号来启动接收端数据采集器工作。结果获得更加稳定的选通时间。结论是这种控制方式减弱了3D激光雷达光选通时间的抖动,增强了3D激光雷达系统实时监测和可控性,使得激光雷达系统发射端能够长期稳定有效的工作。

立体空心血管网水凝胶支架的3D打印工艺研究

搭建同轴喷头打印系统,研究氯化铁溶液对由同轴针头打印出的藻酸盐水凝胶空心圆管的机械强度和成型结构的影响,建立3D打印优化工艺。将质量分数为2%~4%的海藻酸钠和质量分数为4%的氯化钙通过同轴针头打印出空心圆管。将质量分数为0.25%的雾化氯化铁溶液与空心圆管反应得到有氯化铁反应的空心圆管,力学试验发现经过与0.25%氯化铁反应的空心圆管的弹性模量(0.4677 MPa±0.279 MPa(2%海藻酸钠),2.0153 MPa±0.221 MPa(3%海藻酸钠),11.684 MPa±0.332 MPa(4%海藻酸钠))是无氯化铁溶液反应的空心圆管的弹性模量的5.4倍(2%),14.2倍(3%)和43.3倍(4%),其力学强度大大增强。机械强度增强的空心圆管完成了立体网络结构和螺旋结构的复杂类血管网,通过水凝胶溶液将其封装形成生物支架。灌流实验和细胞毒性试验表明该支架具有良好的生物相容性,可有效运输和灌注细胞培养液,满足了组织工程中制造大块软组织的工程化需求。

3D打印机喷头组件结构优化设计

针对3D打印机喷头组件的打印精度低和表面粗糙、安装不便、喷头易堵塞等问题,建立喷头组件装配模型,分析其模型特征。并结合傅里叶热传导定律,利用ANSYS workbench对喷头组件进行热力学分析,经仿真分析和实践应用,对打印头组件和铁氟龙管的结构进行重新优化设计。最后将原始喷头组件和改进后的喷头组件进行比较,得到改善后的打印机喷头堵塞频次明显降低,流畅度更好,打印件表面质量也得到了提高,主要散热部件自身散热效率至少提高8.17%,为3D打印机的进一步推广和发展提供了参考。

新型组合式3D高效预热系统在熔铝炉上的节能示范研究

高温空气燃烧技术中所使用的传统蓄热室存在排烟温度高、阻力大等问题。三维变空间高效换热器是一种高效的换热设备,由于工作温度的局限性,不能直接应用于高温空气燃烧技术的节能降耗。针对这些问题提出一种新型组合式3D高效预热系统,解决传统蓄热室存在排烟温度高、阻力大等问题,克服三维变空间高效换热器应用的局限性,实现高温空气燃烧技术进一步的节能降耗。首先,对3D高效预热系统特点进行介绍,分析二者联合应用于高温空气燃烧技术的可行性。其次,应用3D高效预热系统对某公司一台熔铝炉进行技术改造,并进行实际运行测试和考核分析。结果表明,3D高效预热系统可有效降低系统阻力和排烟温度,减少引风机功耗25%,降低成铝天然气消耗10 Nm^(3)/t,节约天然气成本可达58.5万元/年,经济效益显著。

3D打印技术在飞行装备及微波器件中的应用

3D打印(增材制造)技术是一种新兴的制造技术,在军用和民用领域发挥着越来越重要的作用。本文针对国内外3D打印技术最新进展,特别是3D打印技术在军用武器装备和微波管及毫米波、太赫兹无源组件制造领域的研究进展进行了综述,并对未来3D打印技术在微波管中的应用所面临的挑战进行了分析。

基于PERFORM-3D的筒中筒结构弹塑性时程分析与性能评估

采用PERFORM-3D软件及纤维剪力墙单元,通过对一14层筒中筒结构试验模型进行弹塑性时程分析,并与试验结果对比,验证了软件模型的合理性。通过结构在不同烈度情况下的变形分析,具体研究了该结构的层间位移角分布,并参考美国性能规范ASCE41—06,对结构在弹塑性阶段的性能进行评估。得出在高烈度地震动下结构底部剪力墙出现较大塑性变形,以耗散大部分能量,同时给出相应的设计建议,为同类高层结构弹塑性分析提供参考。

低辐射剂量CT扫描技术行肝3D建模打印的可行性

目的肝3D打印技术已广泛应用,但其带来的高CT辐射剂量问题却容易被忽视。文章旨在探讨低辐射剂量CT扫描技术行肝3D建模打印的可行性。方法回顾性分析东部战区总医院2016年1月-2018年6月间行肝3D建模打印的患者40例。低剂量组(n=20):管电压100 kVp,自动管电流调制技术(ATCM)及自适应统计迭代重建(ASIR)算法;常规剂量组(n=20):管电压120 kVp,管电流250 mA,滤波反投影(FBP)重建算法。两组均采用非离子型对比剂碘海醇(300 mgI/mL)。测量所有患者腹主动脉、门静脉及肝实质三期增强CT扫描的CT值、背景噪声(BN)、容积CT剂量指数(CTDI)及剂量长度乘积(DLP),并计算对比噪声比(CNR)及有效辐射剂量(ED)。将2组CT DICOM原始数据传至3D打印机行肝3D建模打印,对3D建模打印结果进行主观评分。结果 2组患者的一般临床资料、CT值、BN及CNR差异均无统计学意义(P<0.05);而组间CTDI、DLP及ED差异均有统计学意义(P<0.05)。低剂量组患者ED值[(2.58±0.79)mSv]显著低于常规剂量组[(4.02±0.26)mSv],差异有统计学意义(P<0.05)。组间肝3D建模打印结果的主观评分差异无统计学意义(P<0.05)。结论采用低辐射剂量CT扫描技术行肝3D建模打印能够满足临床需要的同时,可明显降低患者所受的CT辐射剂量。

经阴道3D子宫输卵管超声造影在不孕症诊疗中的研究进展

世界卫生组织数据显示全球不孕不育的发生率约为15%,其中输卵管性不孕约占女性不孕症的30%~35%,已经成为影响全球人口发展的重要障碍之一。随着研究的深入,传统的输卵管通液术和X线子宫输卵管造影术在输卵管性不孕症诊断和治疗上的安全性和有效性受到重大挑战。近年来,经阴道3D子宫输卵管超声造影术以其独特的优势开始逐渐取代传统模式,成为输卵管不孕症的首选诊治方式。本文就经阴道3D子宫输卵管超声造影术的发生和发展、有效性和优越性、安全性和不良反应等方面进行综述。

3D-Slicer软件在锥颅软通道治疗高血压脑出血中的应用

目的探讨3D-Slicer软件在锥颅软通道治疗高血压脑出血中的临床应用价值。方法选择2018年1月~2019年2月本院收治的高血压脑出血患者80例,按照随机数字法分为两组,各40例。观察组应用3D-Slicer软件进行引导,对照组按照常规经验,结合术前头颅CT血肿定位,进行盲探穿刺血肿引流术,比较治疗期间两组颅内压及脑灌注压变化情况,统计两组手术相关并发症。结果术后1 d、术后7 d,观察组颅内压均显著低于对照组(P<0.05),观察组脑灌注压均显著高于对照组(P<0.05),观察组术后出现感染、再出血、脑梗死及应激性溃疡的总体比例显著低于对照组(P<0.05)。结论针对高血压脑出血采用3D-Slicer软件定位导航后实施经锥颅软通道治疗,能有效降低颅内压,改善脑灌注压,且手术并发症少,安全性高。

低辐射剂量CT扫描技术在脑动脉3D打印中的应用研究

目的:探讨低辐射剂量CT扫描数据在脑动脉3D打印的可行性研究。方法:将临床拟行脑动脉3D打印的40例患者随机分为2组,每组20例。A组(常规剂量CT扫描方案):120 kVp,350 mA和滤波反投影(FBP)算法;B组(低剂量CT扫描方案):80 k Vp,自动管电流调制技术(ATCM)和自适应统计迭代重建(ASiR)算法;2组对比剂浓度均为350 mgI/mL。采用两独立样本t检验(非正态分布采用Mann-Whitney U检验)来比较2组的临床资料、辐射剂量、CT DICOM数据客观评价指标及2组方案完成3D打印产物质量的主观评分。结果:A、B 2组患者的临床资料差异均无统计学意义(P>0.05)。2组的CT辐射剂量差异具有显著统计学意义(P<0.05),B组辐射剂量[(1.30±0.47)m Sv]较A组[(4.15±0.62)m Sv]减少约68.7%。2组脑动脉3D打印结果主观评分差异无统计学意义(P>0.05)。2组CT DICOM数据客观评价指标:A组的背景噪声(BN)明显高于B组(P=0.000),而A组的信噪比(SNR)及对比噪声比(CNR)均低于B组(P=0.000)。结论:采用80 kVp、ATCM技术及ASIR算法的数据行脑动脉3D打印,在保证3D打印质量的同时,可以有效减低辐射剂量。

3D打印技术辅助下针刺翼腭神经节治疗咽鼓管功能障碍的临床研究

目的探讨针刺翼腭神经节治疗咽鼓管功能障碍的临床疗效。方法选取2017年11月至2018年12月南京中医药大学附属医院耳鼻咽喉科门诊收治的60例(78耳)诊断为分泌性中耳炎的患者,分为欧龙马滴剂对照组和3D打印技术辅助下针刺翼腭神经节联合欧龙马滴剂治疗组,各30例,2组患者均治疗4周,采用咽鼓管功能问卷(ETDQ-7)调查及纯音测听、声阻抗检查对临床疗效进行评价。结果治疗后2组ETDQ-7评分都显著降低(P<0.05),治疗组在ETDQ-7评分及纯音测听、声阻抗检查均优于对照组(P<0.01),治疗组有效率(92.5%)和远期随访疗效(87.5%)均优于对照组(71.1%,55.2%)(P<0.05~0.01)。结论 3D打印技术辅助下针刺翼腭神经节操作简易,安全有效。

3D打印在凝汽器冷却管方面的应用

3D打印冷却管,在建立数学模型后,不再需要传统的刀具、夹具和机床或任何模具,从而进行大批量生产,可在腐蚀程度过轻时更换,缩短有效的产品研发周期及更换时间,以保证机组效率。此外,还能提高冷却管硬度、强度、耐腐蚀、减轻自身重量等;节省材料(尤其是金属材料),不用除掉边角废料,可提高打印材料的利用效率,进一步降低生产成本,并能提高保护冷却管精度,减少其细小缝隙的存在,保证使用时长。