异质金属曲面夹层板上面板抗撞性能研究及多目标优化CSCD

异质金属曲面夹层板具有优越的综合性能(比刚度高、耐撞性、轻质等),在航空、航天、高速列车、船舶等领域得到广泛应用。针对异质金属曲面夹层板上面板,进行了碰撞载荷作用下的性能研究。采用有限元数值模拟的方法对碰撞过程中不同上面板参数夹层板的综合性能进行数值求解计算,并利用响应面方法构建了上面板综合指标近似函数,从而得到上面板参数对夹层板抗撞性能影响规律。     

异质金属曲面夹层板上面板抗撞性能研究及多目标优化

异质金属曲面夹层板具有优越的综合性能(比刚度高、耐撞性、轻质等),在航空、航天、高速列车、船舶等领域得到广泛应用。针对异质金属曲面夹层板上面板,进行了碰撞载荷作用下的性能研究。采用有限元数值模拟的方法对碰撞过程中不同上面板参数夹层板的综合性能进行数值求解计算,并利用响应面方法构建了上面板综合指标近似函数,从而得到上面板参数对夹层板抗撞性能影响规律。     

车辆薄壁结构碰撞性能的研究

利用显有限元方法对4种典型车用薄壁结构进行正碰碰撞仿真,得到其的变形模式、吸能规律、冲击力、速度等一系列参数,分析了不同结构耐碰撞性能的优劣,为车辆耐碰撞性能的设计和构件截面形状的优化奠定了基础。     

薄壁构件的长度对抗撞性影响的研究

基于显式有限元技术,采用响应面法,以结构的比吸能为优化函数,以提高吸能原件的抗撞性为目的,研究正方形截面金属薄壁构件的长度对抗撞性的影响;经过数值分析,得出正方形截面薄壁构件的比吸能关于构件长度和截面边长的变化规律,这些规律可以用于实际吸能原件的设计,并为进一步研究奠定基础.     

基于COPRAS方法的汽车保险杠多工况耐撞性能研究

考虑汽车低速碰撞中的,使用复杂比例评价方法(COPRAS)对不同截面构型的汽车保险杠的耐撞性能进行综合评估与研究。首先,分别在对中碰撞和角度碰撞工况下,建立等质量的六种不同防撞梁截面构型的保险杠的有限元模型并进行仿真分析,选取碰撞加速度、碰撞时间、保险杠最大变形量和保险杠系统吸收能量为评价指标,然后,使用COPRAS评价方法对六种不同防撞梁截面构型的保险杠的综合耐撞性能进行评估,最后,得到具有最优综合耐撞性能的保险杠设计并进行耐撞性能分析。由此得出,COPRAS方法可以高效、合理地用于汽车保险杠的安全设计。     

端部方锥形薄壁构件的抗撞性尺寸优化

基于显式有限元技术,采用响应面法,以结构的比吸能为优化函数,以提高车辆吸能原件的抗撞性为目的,研究正方形截面金属薄壁构件的端部锥形尺寸对抗撞性的影响.经过数值分析,得出端部为方锥形的正方形截面薄壁构件的比吸能关于锥形长度和小锥边长的变化规律,这些规律可以用于实际吸能原件的设计,为进一步研究奠定基础.     

薄壁管轴向冲击的数值模拟与吸能优化

从抗撞性角度观察车辆设计,薄壁构件具有良好的吸能性能,为了深入探讨车辆吸能元件抗撞的性能,应用LS-DYNA对不同正多边形截面薄壁管进行计算机数值模拟,旨在获得工程抗撞设计中对某些抗撞部位具有借鉴性的吸能元件。采用斐波那契(Fibonacci)搜索对正多边形截面薄壁管吸能最大对应的最佳边数的搜索求解,得在正多边形截面薄壁管冲击压缩相同长度时,正十一边形截面薄壁管的吸能最大。     

基于耐撞性的汽车多腔结构吸能盒轻量化设计

为了在保证耐撞性的前提下实现汽车吸能盒的轻量化,通过有限元碰撞仿真对比确定了符合要求的吸能盒结构,并采用基于近似模型的优化方法获得了性能最优的多腔结构吸能盒设计方案.首先建立了多种截面形状吸能盒的有限元模型,使用有限元软件进行了碰撞仿真分析.通过对单腔结构吸能盒与不同截面的多腔结构吸能盒的碰撞性能进行评价与决策,确定了符合要求的吸能盒截面形状.其次对此截面吸能盒的内外壁厚进行试验设计,拟合了碰撞性能参数的响应面模型,建立了以吸能盒内外壁厚作为设计变量,以比吸能最大作为目标函数的数学优化模型,并进行了优化设计.结果表明,采用该方法得到的最优方案能够在保证碰撞安全性的基础上实现多腔结构吸能盒的轻量化设计.     

八边形组合结构薄壁管耐撞性研究

为提高薄壁管件耐撞性,在基础截面薄壁管的基础上,设计了八边形组合结构薄壁管件,并通过理论计算和数值仿真对不同的组合结构以及基础截面薄壁结构进行了轴向压溃动力学分析,从而对比研究了八边形组合薄壁结构的耐撞性能.研究结果表明:组合薄壁结构的整体耐撞性相对于基础截面薄壁结构有着极大的提高,其中比吸能平均提高了63.6％.在组...     

典型金属加筋板鸟撞实验研究

以典型金属加筋板为鸟撞实验研究对象,采用数字图像相关法的非接触测试方法实现鸟撞区域测试点三维位移信息的测量,与传统的接触式测试方法相比,测试精度和可靠性得到了提高。并通过分析高速摄像结果,得到数值模拟中鸟体应采用的描述流体行为的本构模型。最后通过对比不同撞击点的实验结果,确定了典型加筋板的鸟撞危险点,验证了加筋板不同的蒙皮-筋条间连接强度对结构抗鸟撞性能的影响。     

聚氨酯夹芯板发泡缺陷电磁超声导波快速检测

聚氨酯夹芯板在生产中因发泡不均容易在聚氨酯泡沫层形成空洞型缺陷,直接影响其保温效果,为此提出了一种从金属板外侧实施的电磁超声SH导波检测的快速检测方法。通过理论分析、解析推导、仿真计算和试验验证,建立了聚氨酯夹芯板中的SH导波透反射比系数与激励参数之间的关系,结果表明,当磁铁间距为4.5 mm时,控制SH0导波入射角度为75°,能够得到最佳的检测效果。同时也进一步验证了SH0导波接收信号幅值与缺陷面积、缺陷深度均基本上呈线性关系。在此基础上,提出了一种可应用于实际检测的缺陷当量大小评价方法。通过评价公式进行修正,可消除因收、发探头之间距离变化引起的缺陷信号评价波动问题,这对于后期实现缺陷定位具有较好的指导作用。     

高压静电场下废弃印刷线路板颗粒的动力学研究

对废弃印刷线路板进行资源化回收时,金属和非金属的有效分离是关键。采用高压静电分离法对破碎后的废弃印刷线路板颗粒进行分选时,要求金属颗粒能够顺利脱离接地圆辊电极,而非金属颗粒应当有效吸附在接地圆辊表面。通过对金属颗粒和非金属颗粒在高压静电场中的动力学分析,得到了保证金属颗粒脱离接地圆辊电极和非金属颗粒有效粘附于接地圆辊表面的条件。对高压静电分离操作中的颗粒粒径和接地圆辊电极转速与电场强度之间的关系进行了分析讨论,提出了优化分选效果的参数配置,对于提高分选效率和分离纯度具有一定的参考价值。     

复合轧制氧化铝-铝基复合材料工艺与界面结合机制

通过6061铝合金双板复合轧制成功制备内含微弧氧化陶瓷颗粒的新型复合板,为金属基复合材料制备开辟一条新途径。用撕裂法测试复合板的结合强度结果表明：铝板前处理、轧制温度和压下率都对该复合板的结合强度(决定复合材料力学性能的重要指标)有明显的影响,并在本试验温度范围内结合强度出现了极大值。由温度因素研究得知,与裂口机制和镶嵌机制相关的回复再结晶软化、金属原子动能升高和氧化隔离3个次级机制存在于本试验研究条件下,并且由温度因素影响它们的主导作用地位。在轧制过程中微弧氧化铝合金表面陶瓷层破裂形成的陶瓷颗粒,使双板构成镶嵌结合关系。     

Experimental studies on cryogenic recycling of printed circuit board

Printed circuit board (PCB) recycling is an important challenge for today’s industry. This paper presents results from a study of cryogenic decomposition as a potential alternative recycling method for obsolete printed circuit board scraps. In this method liquid nitrogen is employed as a cryogen to form an environment as low as 77 K for PCB treatment. In order to test the effect of thermal stress set-up during the rapid cryogenic treatment, impact tests were used to simulate the current shredding process. The treated PCB scraps were investigated under a monocular microscope with a 200X magnitude for micro-crack effect observation. Fatigue behavior of the boards was also examined by repeating the cryogenic treatment. The experimental results, as analyzed, demonstrated no obvious support to this alternative PCB recycling method. The energy absorbed during the impact tests for the cryogenically treated boards is insignificantly different from those without the treatment.     

基于激光传感器的蜜胺板检测系统研制

蜜胺板广泛用于印制电路板钻孔加工中的垫板辅料,随着机加工精度的要求越来越高,蜜胺板厚度在线精确检测成为迫切需要。针对蜜胺板厚度的自动在线检测系统的开发问题,采用非接触式的位移传感器,研制了基于激光三角法的蜜胺板测厚系统。系统借助DELPHI开发了控制系统的上位机操作管理软件,对采集卡和外围辅助装置的指令实时传输、处理。研制的蜜胺板测厚系统操作简便,有较强的可靠性和运行效率。现场应用表明,该测厚系统对蜜胺板厚度的测量精度达0．01mm,测量范围为0—10mm。     

Low velocity impact denting of HSSA lightweight sandwich panel

Slow speed impact by a small mass can cause residual denting without perforation of a fibrous core sandwich panel that has thin facesheets. Denting depends on the kinetic energy, compliance and nose shape of the colliding body as well as the compliance and mass density of the sandwich panel. Collision experiments were carried out with fibrous core sandwich panels of different sizes struck by colliding spheres at small velocities. Analytical models based on either quasi-static or dynamic deformation of plates were developed to calculate the impact force during low speed impact on circular sandwich panels. Finite element analysis using ABAQUS was performed to calculate impact damage on sandwich panels. Results of the analytical and numerical models and the experimental measurements were compared. The dependence of damage on both structural parameters and impact variables was investigated.     

Development of application technique of aluminum sandwich sheets for automotive hood

Objective of this study was to develop basic techniques in order to apply aluminum sandwich sheets for an automotive hood part. The aluminum sandwich sheet is the material fabricated by adhering two aluminum skins to one polypropylene core. When it has the same bending stiffness as a steel sheet, it is 65% lighter than the steel sheet and 30% lighter than an aluminum alloy sheet. Therefore, it is notified exclusively as good substitutive materials for a steel body to improve the fuel efficiency. Through aluminum sandwich sheet, however, it has relatively lower formability than that of the steel sheet for automotive application. In this study, we developed application techniques of the aluminum sandwich sheet for automotive hood. The various formability evaluations were carried out in order to secure the fundamental data for the measurement of sheet metal forming and the establishment of optimum application conditions of the sandwich sheet. From these results, it was found that the sandwich sheet could reduce the weight and maintain the flexural rigidity simultaneously comparing to the steel sheet.     

电液半主动馈能悬架非线性建模与协调性优化

为了协调电液半主动馈能悬架的减振性能与馈能性能,建立了基于电液作动器的半主动馈能悬架的非线性模型,开展了力学特性试验,并采用最小二乘递推算法对系统模型进行了参数辨识。分析了电液作动器主要参数对悬架减振性能和馈能性能的影响,采用遗传算法对电液作动器主要参数进行了优化,并进行了台架试验。试验结果表明,频率2Hz、幅值30mm的正弦路谱输入下,优化后的电液半主动悬架簧载质量加速度降低22.23%,馈能功率提高40.51%,在保证满足一定的车辆乘坐舒适性和行驶安全性的要求下,悬架馈能性能得到明显提高。     

智能型电路板浸焊机的设计与探讨

主要介绍了浸焊机的一种全新结构设计以及从电路板的抓取、焊锡面的检测方法等浸焊工艺上进一步探讨如何提高电路板的浸焊质量.同时对助焊剂、焊料的选择进行了深入探讨,进一步探究影响浸焊质量的因素.     

Simultaneous optimisation of multiple performance characteristics in micro-EDM drilling of titanium alloy

Micro-electrical discharge machining (micro-EDM) has become a widely accepted non-traditional material removal process for machining conductive and difficult-to-cut materials effectively and economically. Being a difficult-to-cut material, titanium alloy suffers poor machinability for most cutting processes, especially the drilling of micro-holes using traditional machining methods. Although EDM is suitable for machining titanium alloys, selection of machining parameters for higher machining rate and accuracy is a challenging task in machining micro-holes. In this study, an attempt has been made for simultaneous optimization of the process performances like, metal removal rate, tool wear rate and overcut based on Taguchi methodology. Thus, the optimal micro-EDM process parameter settings have been found out for a set of desired performances. The process parameters considered in the study were pulse-on time, frequency, voltage and current while tungsten carbide electrode was used as a tool. Verification experiments have been carried out and the results have been provided to illustrate the effectiveness of this approach.