箱装电子仪器安全跌落冲击数值模拟方法研究

为正确评估跌落冲击对箱装电子仪器可靠性的影响,确定了合理的包装参数和设计流程,科学指导运输与试验,分别采用理论分析和有限元计算方法对箱装电子仪器垂直跌落的情况进行了仿真,得到了垂直跌落条件下电子仪器最大加速度和最大位移随跌落高度与缓冲垫弹性模量变化的规律。结合产品脆值,确定了产品储运过程中的最大堆垛高度,并得到了合理的包装设计流程,从而为有效指导产品包装设计、实体试验和储运安全提供了理论依据。     

机械冲击耐撞性与稳健设计

碰撞冲击是机电产品损坏失效的常见原因,轻则造成产品外形丧失美观,重则造成产品内在功能失效,甚至机毁人亡,因而机械产品的耐撞性受到日益广泛的关注。本文从产品跌落冲击和运载工具碰撞两个领域论述了机械系统碰撞动力学和耐撞性设计研究的发展、两领域耐撞性研究的阶段性和特点,分析了机械冲击耐撞性中的冲击参数到性能参数传递过程中的不确定性,进而探讨了机械系统产品耐撞性稳健设计优化框架。     

Fatigue and fracture assessment for reliability in electronics packaging

Modern electronics products relentlessly become more complex, higher in density and speed, and thinner and lighter for greater portability. The package of these products is therefore critical. The reliability of the interconnection of electronics packaging has become a critical issue. In this study, the novel testing methods for electronic packaging are introduced and failure mechanisms of electronic packaging are explained. Electronics packaging is subjected to mechanical vibration and thermal cyclic loads which lead to fatigue crack initiation, propagation and the ultimate fracture of the packaging. A small-sized electromagnetic-type bending cycling tester, a micro-mechanical testing machine, and thermal fatigue testing apparatus were specially developed for the reliability assessment of electronics packaging. The long-term reliability of an electronic component under cyclic bending induced high-cycle fatigue was assessed. The high-cycle bending-fatigue test was performed using an electromagnetic-type testing machine. The time to failure was determined by measuring the changes in resistance. Using the micro-mechanical tester, low cycle fatigues were performed and compared with the results of a finite element analysis to investigate the optimal shape of solder bumps in electronic packaging. Fatigue tests on various lead-free solder materials are discussed. To assess the resistance against thermal loads, pseudo-power cycling method is developed. Thermal fatigue tests of lead-containing and lead-free solder joints of electronic packaging were performed using the pseudo-power cycling tester. The results from the thermal fatigue tests are compared with the mechanical fatigue data in terms of the inelastic energy dissipation per cycle. It was found that the mechanical load has a longer fatigue life than the thermal load at the same inelastic energy dissipation per cycle.     

头戴式耳机跌落冲击的仿真分析与实验

目的对跌落测试中的破坏风险进行预测和改进,从而提升设计效率。方法基于Abaqus,对头戴式耳机进行整机跌落仿真分析,对其在规定高度下撞击地面的整机结构耐冲击性进行研究,考虑到材料的非线性和应变率效应,采用质量缩放、应力包络图等技术来提升仿真效率,并将高速摄影下的实际跌落过程与仿真结果进行对比。结果数值仿真预测了产品在跌落过程中的破坏风险,并对优化后的设计进行了验证,与实验结果高度吻合。结论在头戴式耳机一类消费电子产品的设计中,合理利用数值仿真,可有效缩短产品研发周期,降低研发成本,提升产品质量,从而提高产品的市场竞争力。     

Residual Capacity Estimation for Lead–Acid Batteries Used in Automobiles by the Method of Median Internal Resistance

The purpose of this study was to investigate the method of residual capacity estimation for lead–acid batteries used in automobiles. First, relation charts for the internal resistances of a battery at various load currents to residual capacity percentages were established, and the relation charts for all load currents were then combined to obtain the corresponding residual capacity by calculating medians. The experimental equipment included lead–acid batteries for automobiles, an electronic loader, an internal resistance tester, and test cables. The experimental procedures were discharging the battery with the electronic loader, using the internal resistance tester to record the internal resistance, voltage, and temperature of the battery, and then transmitting the data to a computer via the test cables for analysis. The experiment obtained nine sets of data, which were recorded in Excel and illustrated using charts. The medians obtained from combining the internal resistance with the residual capacity percentages were used to generate the relation charts for the internal resistances at various load currents to the residual capacity percentages. Finally, 60 Ah was used as the normal capacity to estimate the residual capacity discharging time. Furthermore, a curve-fitting approach for determining the relation equation between internal resistances and capacities was used to replace the table look-up method for residual capacity estimation. The results revealed that the estimation errors after correction were acceptable.     

适于电商物流蛋类产品的包装设计

目的研究EPE材料包装电商物流鸡蛋的缓冲结构。方法采用EPE材料,设计圆形、方形和梅花形等3种蛋托缓冲结构,外包装采用瓦楞纸箱,利用跌落试验机对包装件进行模拟跌落试验。结果通过对3种包装进行跌落试验,得到最大响应加速度分别为31.26g,43.76g,46.25g,均小于鸡蛋的脆值50g,其中圆形蛋托跌落的最大响应加速度最小,对鸡蛋的保护性最好。结论只要EPE缓冲结构设计合理,完全能够满足蛋类产品的电商物流包装要求。     

Impact Oscillator Model for the Prediction of Dynamic Cushion Curves of Open Cell Foams

Cushion curves enable packaging designers to optimize a design solution for a given product fragility and expected distribution environment drop height. The industry accepted techniques for developing these curves are time intensive and devoid of a physical understanding of the materials and the physics involve in energy absorption. This paper delves into a qualitative understanding of the dynamics of a platen impacting an open cell foam cushion material. An hyperelastic material model is used to describe the foam's nonlinear stress–strain relationship, while its damping and hysteretic behaviour are represented with linear viscoelasticity. Using a simple nonlinear, discontinuous model of a drop test along with numerical simulations, the study examines the physics of the impact. The numerical studies show that the model is able to provide predictions of the shock pulse's shape, duration and amplitude at various static stresses and drop heights. The dynamic cushion curves generated by the model retain the characteristic concave upward ‘trough’ shape of the experimental curves. Furthermore, the model shows that the optimal amplitude of shock absorbed for a given set of drop conditions depends on the foam's thickness and cross‐sectional area. Lastly, the model is validated using the comparison of a predicted curve and experimental data captured using a cushion tester. Copyright © 2014 John Wiley & Sons, Ltd.     

Rate-dependent mechanical properties of cured conductive adhesives and drop impact behavior of adhesive bonding points in electronic interconnection

Journal of Materials Science: Materials in Electronics - Given the boom of portable electronic products and the increasing risk of drop impact load in electronic interconnection points, the...     

某型包装箱跌落动力学仿真分析

目的研究某新型导弹包装箱跌落工况下的冲击动力学响应,校核箱体结构是否满足设计要求。方法采用有限元仿真技术,研究包装箱结构跌落冲击动力学行为。建立箱体结构三维仿真模型,分析水平跌落和棱边跌落等2种工况,得到箱体的应力分布以及加速度响应,进一步对仿真分析结果的可靠性进行试验验证。结果 2种跌落工况下,箱体所受最大应力均小于材料的屈服极限。经跌落试验测试,箱体结构完好,无损伤和变形,试验结果与仿真结果吻合。结论有限元分析结果合理可靠,包装箱结构性能满足设计要求。     

现场发泡包装结构设计系统的开发与应用

根据缓冲包装动力学理论,开发了一套现场发泡包装结构优化设计系统,以适应各种产品的缓冲包装设计。以卫生洁具为例,使用该优化系统设计了该产品的缓冲包装结构,并采用实体跌落实验证实了此种包装结构设计的良好缓冲效果。     

Cushioning properties of convoluted foam

Convoluted polyurethane foam was tested for its cushioning ability in controlled drop tests using a cushion tester. The purpose of the tests was to relate the peak acceleration transmitted to the falling weight to key geometric features of the cushion, such as base thickness and area, along with finger height and spacing. It was found that the fingers had the effect of reducing the impact velocity in a predictable manner, allowing the convoluted cushion to be treated as a block design so that published cushion curves for the same material could be used to obtain the peak acceleration. In effect, convoluted foam behaves like a block cushion of the size of its own base in a drop from a reduced height, the reduction being several times the finger height. Copyright © 1999 John Wiley & Sons, Ltd.     

纸浆模塑托盘对角刚度的跌落试验测试

通过跌落试验机对纸浆模塑平托盘进行对角线刚度试验,分析了其从不同高度跌落后的变形,校核了托盘的对角刚度,并利用数字图像相关方法对高速摄像机采集的图像进行了定量分析,得到了纸浆模塑材料的弹塑性力学特性,从而可以定量评定托盘抗冲击变形能力及对货物的承载能力。为纸浆模塑托盘的设计提供了重要指导。     

CAD navigation and diagnostics by linking ATE and EDA

This paper describes a specific methodology and software that links automated test equipment (ATE) and electronic design automation (EDA) tools to identify and diagnose failures at the layout level. The ATE software, named wafer fail layout map (WFLMAP), works in concert with the EDA integrated circuits (IC) design database and provides computer-aided design (CAD) navigation and correlation between the tester failure data and IC design data. With this approach, layout-level defect diagnosis is achieved at the individual chip level, as well as at the wafer level. This method can also be used for improved design for manufacturing (DFM).     

电竞用户心流体验对感知价值和用户黏度的影响

目的 以电子竞技用户为研究对象,探究心流体验的测量维度,揭示心流体验各维度对感知价值（享乐价值和功利价值）和用户黏度的影响机制,并从心流体验的专业视角,探索电竞产品的设计思路。方法 通过文献研究、专家访谈和问卷调查先后进行预调研和正式调研,用所获数据进行分析和结构方程建模。结果 电子竞技用户的心流体验维度由时间感异常、自我意识丧失和控制感构成。心流体验对感知价值中的享乐价值维度具有显著的正向影响;感知价值对用户黏度具有显著的正向影响;心流体验对用户黏度不具有显著的正向影响。结论 电子竞技用户的心流体验主要通过享乐价值间接地正向影响用户黏度,心流体验中仅有一个维度（自我意识丧失）可以通过功利价值正向影响用户黏度。     

High-G drop impact response and failure analysis of a chip packaged printed circuit board

This paper is concerned with constructing a high-G drop impact test condition for investigating the impact-induced failure phenomenon of the solder ball array located in the chip packaged printed circuit board. An impact environment satisfying the JEDEC B service conditions, requiring a 0.5 ms half-sine impact pulse duration with a peak acceleration at 1500 G, were constructed using an instrumented drop tower tester. Fifteen wafer-level CSP chips were installed on a standard printed circuit board (PCB) with a dimension of 132×77×1 mm³. A number of these chip packaged PCB bonded with four different compositions of solder joints with or without lead using the surface-mounted technology (SMT) were studied. During the drop impact tests, the chip packaged PCB circuit was monitored using the multi-event detector system (ETAC) to examine whether circuit fails or not. In addition, the drop impact dynamic response of the PCB and the acceleration at the prescribed location of the drop table were recorded and analyzed. Transient stress responses in the solder joints were provided using the LS-DYNA explicit code. Numerically predicted failure locations of the solder joints are close to those observed from actual drop impact experiments.     

框架式灯具缓冲包装结构设计

目的 在绿色包装设计的新要求下,改进传统塑料包装方案,以框架式灯具的安全运输为例,设计一种面向框架类产品的全瓦楞纸板的绿色缓冲包装.方法 以缓冲包装六步法为依据,利用平面材料立体化造型设计方法,设计全瓦楞纸板缓冲包装结构,并利用E和B型瓦楞纸板分别制作出2套结构尺寸相等的缓冲包装.根据ISTA-1A标准对2组包装件进行跌落试验,通过安装在灯具上的传感器测试的数据及包装件的变形,研究瓦楞板厚度对包装件缓冲性能的影响,综合评价包装件的缓冲性能.结果 对2套不同厚度的瓦楞纸板缓冲包装结构,分别进行一角、三棱、六面的跌落测试,得出了相应加速度-时间曲线和包装件变形图.结果 表明,跌落过程中灯具系统的最大加速度为684.17 m/s2,小于灯泡脆值(784 m/s2),并且灯架未变形,灯泡及配件均未损坏,B型瓦楞板制作缓冲包装结构在试验后相对于E型瓦楞板制作的变形更小.结论 2套全瓦楞缓冲包装具有良好的缓冲性能,厚度大的纸板具有更好的缓冲效果,能有效缓冲框架灯具在物流运输过程中所受到的冲击,适用于装卡在其他框架类产品的两端,具有较好的使用价值和应用前景.     

泡沫铝夹芯板压入和侵彻性能的实验研究

利用MTS和落锤试验机研究了由复合材料面板和闭孔泡沫铝芯层组成的夹芯板结构在压入和侵彻时的变形和失效行为,并通过引入无量纲参数——能量吸收效率因子,探讨了一些关键参数对夹芯板压入和侵彻性能以及能量吸收性能的影响,如冲击能量、面板厚度、芯层厚度及相对密度、压头/锤头形状和边界条件等。结果表明夹芯板的破坏主要集中在压头作用的局部区域内。夹芯板的能量吸收效率对其结构参数比较敏感,增加上层面板厚度、芯层厚度或芯层相对密度能够有效地提高夹芯板结构的能量吸收能力以及抵抗压入和侵彻的能力,而下层面板厚度的对夹心板抗侵彻性能的影响不明显。不同的压头/锤头形状和边界条件对泡沫铝夹芯板的压入和侵彻响应以及能量吸收性能影响明显。     

热致液晶共聚酯/PA6/RSMA原位复合材料2.力学性质与破坏行为

选用Vectra A950热致液晶共聚酯（LCP）制备热致液晶共聚酯（LCP）/聚酰胺6（PA6）/苯乙烯-马来酸酐无规共聚物（RSMA）三元共混物。并注射成型制得复合板材。研究三元LCP/PA6/RSMA原位复合材料的形态结构、力学性质和破坏行为。结果表明,PSMA是LCP/PA6复合材料的有效增容剂。RSMA的加入有利于LCP在PA6基体中原位成纤,增强了两相之间的界面粘接。加入RSMA后,LCP/PA6原位复合材料的杨氏模量、抗拉强度和抗冲击强度明显提高。RSMA能延长LCP/PA6复合材料的裂纹引发时间、增加裂纹引发能和总冲击能。对LCP/PA6原位复合材料有增韧作用。RSMA的加入量存在一临界值。     

薄膜紧固包装设计与性能研究

目的 针对现有电子产品缓冲包装存在的物料复用率低、仓储空间利用率低、不够绿色环保等问题,设计一种针对轻小型产品的薄膜紧固结构的绿色减量化包装.方法 将性能良好的TPU塑料薄膜用水性胶粘贴在一片式的瓦楞纸板上,折叠成一种薄膜紧固结构的包装件,通过测定纸板和薄膜的物理性能,确定基材的选择标准,对薄膜紧固包装件进行加速老化、跌落和振动试验,验证薄膜紧固包装的可靠性.结果 胶水的固化工艺对薄膜的剥离强度有一定影响,在常温下薄膜复合包装已经具有较好的可靠性,高低温交变的条件下胶水的粘结强度会有不同程度的降低.跌落和振动试验结果表明,样品的外观和功能无损,该薄膜紧固包装能满足在运输过程中的振动和跌落冲击防护要求.结论 可靠性高的薄膜紧固包装需满足的条件,当180°剥离时,剥离力不低于20 N;当0°剥离时,剥离力不低于80N.该薄膜紧固包装能明显降低包装体积,节约仓储物流成本,再生利用性好,TPU可降解,也易重复加工循环使用,能满足运输要求,可为电子类产品的降本环保缓冲包装提供设计思路.     

Strain rate effect on the fatigue failure of thin PVD coatings: An investigation by a novel impact tester with adjustable repetitive force

Physical vapor deposition (PVD) coated surfaces are often subjected to repetitive impact loads. In such cases, the strain rate’s effect on the coating fatigue failure is pivotal. This effect was investigated via a novel impact tester which facilitates the modulation of the applied impact force versus the time through an adjustable piezoelectric actuator. Using the developed test arrangement, impact loads of various patterns, frequencies and durations were generated and the coated specimens’ surface response and film fatigue fracture were captured. Based on these results, it was possible to correspond impact forces of various data to equivalent quasi static ones which induce approximately the same coating and substrate deformation. At the latter loads, the coated specimen deformation was determined by Finite Element Method (FEM) calculations taking into account elastic–plastic film and substrate properties attained by an analytical evaluation of nanoindentation results. Moreover, strain, strain rate combinations insuring film fatigue endurance after one million impacts were estimated.