聚氨酯蜂窝纸板静力学性能和吸能性能

将聚氨酯填充到蜂窝纸板的孔隙中制作了聚氨酯蜂窝纸板复合材料并对其进行静态压缩试验,进而对其吸能特性进行研究,并对影响复合材料的一些因素进行逐个分析,找到它们影响复合材料静态缓冲性能的内在规律.结果表明:复合材料的弹性极限(从0.224 0 MPa提高到0.542 2 MPa)和屈服应力(约为填充前的3～4倍)较单纯蜂窝纸板增长明显;单纯蜂窝纸板材料和聚氨酯蜂窝纸板复合材料的抗压强度和屈服应力随着蜂窝孔径的增大而减小,随着厚度增大略有提升,孔径对其力学性能的影响非常显著;复合材料吸能量较复合前2种材料大幅增加,约为复合前2种材料吸能量总和的1.85倍;吸能效率和理想吸能效率都优于复合前2种材料.     

组合蜂窝结构的面内压缩及吸能性能

针对一种新型组合蜂窝结构(SCCH)开展研究,该结构将方形管与圆形管进行组合,充分发挥了圆形管的吸能优势和方形管的变形优势。通过试验与有限元仿真,对比了SCCH结构与传统圆形蜂窝结构(CH)在面内压缩的力学性能和不同应变时的变形行为。结果表明,SCCH结构的总吸能为0.198 kJ、平均压缩力为5.50 kN、初始峰值压缩力为6.80 kN、比吸能值为6.22 kJ/kg,均优于CH结构。此外,SCCH结构的比吸能明显高于其他常见的蜂窝结构,具有优异力学性能和吸能性能的SCCH结构,可为设计具有高吸能能力的蜂窝结构提供有益借鉴和设计基础。     

蜂窝纸板缓冲机理探讨

从蜂窝胞元密闭气囊的作用和开槽工艺的作用两个方面,对蜂窝纸板缓冲机理进行了理论预测与分析。采用3种开槽方式对30 mm厚蜂窝纸板进行静态压缩试验,考察蜂窝胞元中的密闭气体以及开槽工艺对蜂窝纸板缓冲性能的影响。试验结果表明:对蜂窝纸板进行开槽处理可以降低其起始屈服应力,提高其塑性平台区的缓冲性能,与理论预测相符。     

蜂窝纸板与瓦楞纸板组合结构的缓冲特性

在MTS810材料试验机上,对瓦楞纸板、蜂窝纸板及其组合结构三种材料进行了压缩试验,并将组合结构与另外两种材料的缓冲特性曲线进行比较,得出如下结论：组合结构兼具有两者的优点,对于小幅荷载和较大载荷都有良好的缓冲能力.     

组合蜂窝纸板缓冲性能的静态试验研究

通过静态压缩试验,研究不同面积蜂窝纸板叠置组合的缓冲性能.阐述了组合的蜂窝纸板的静态压缩过程,试验表明组合的方式能改善蜂窝纸板的缓冲性能.同时还选择不同面积板组合情况进行对比分析,得出了板面积变化对整体缓冲性能的影响.     

铝合金保险杠吸能盒碰撞吸能特性

为了改进某轿车保险杠的吸能特性,同时实现保险杠轻量化设计,建立吸能盒有限元模型,基于LS-DYNA软件进行了碰撞仿真。对5种不同截面形状的单腔铝合金吸能盒和4种多腔铝合金吸能盒的吸能特性进行了对比分析,探讨了壁厚对碰撞吸能特性的影响。研究表明:在5种单腔结构中,八边形截面形状吸能盒吸能特性最好;多腔结构吸能盒的吸能特性比单腔结构显著提高;在一定范围内增加吸能盒壁厚,吸能量和比吸能均显著增加。     

厚径比对高阻尼橡胶材料的缓冲吸能特性实验

为减少深部强扰动诱发的岩石冒落、岩爆等动力灾害,将具有良好防冲和吸能特性的高阻尼橡胶材料应用于拟研发的新型小应变吸能锚杆中.为系统评价厚径比对高阻尼橡胶材料缓冲吸能的影响,采用落锤冲击系统和分离式霍普金森压杆(SHPB)装置,对不同厚径比的高阻尼橡胶试样和"橡胶-花岗岩"组合试样进行冲击实验.落锤实验结果表明,相同冲击...     

具有高效吸能特性的新型仿蜂窝多级薄壁结构

针对现有薄壁结构存在比吸能不高、压缩力效率较低的问题,以蜂窝为原型,模拟蜂窝多级嵌套结构,进行仿生结构优化设计。为了更好地探究形状参数对吸能能力的影响,进一步以相对旋转角度及加强柱直径为设计变量,设计了共20种仿蜂窝多级薄壁结构。运用3D打印技术,制备了尼龙材质的仿蜂窝多级薄壁结构样件,并进行准静态压缩试验。最后,对比分析了数值模拟结果与试验结果,得出以下结论：本文吸能能力最强的模型为YMT20-3.6,比吸能达到了10.87 J·g-1,较初始模型YMT0-0提高了约86%;旋转角度越大,加强柱直径越大,模型截面面积分布越均匀,模型变形模式也趋于对称,其能量吸收能力也更强;较大的旋转角度拥有更优异的吸能能力,但是其压缩力效率较小。增大模型加强柱直径能够减少旋转角度对压缩力效率的影响,提高模型的压缩力效率,从而得到吸能能力强、压缩力效率高的薄壁结构。     

泡沫铝叠片的压缩性能与高gn值冲击吸能研究

对不同密度、孔隙率、孔径的泡沫铝叠片进行了静态压缩试验，通过试验现象和结果研究了泡沫铝叠片的缓冲吸能本领．对采用泡沫铝叠片保护侵彻过程中弹载存储测试电路模块进行了初步的理论分析．实验和理论研究表明：泡沫铝叠片在准静态下具有良好的缓冲性能，利用它对测试电路模块进行保护是可行的．     

一种确定六边形蜂窝芯材共异面弹性模量的简单有限元法

参照相关实验标准,通过模拟实验载荷条件的方法建立了用来求解六边形蜂窝芯材共异面弹性模量的有限元方法.通过改变参数,利用该方法进行了大量模拟计算.将计算结果与已有理论计算结果进行比较分析,发现两者吻合较好,验证了该有限元模拟方法的正确性.     

正方形蜂窝纸板面内压缩力学性能仿真分析

采用SolidWorks软件仿真分析结构性能的功能,研究了正方形蜂窝结构面内压缩力学性能。结果表明,当蜂窝厚度一定时,蜂窝边长越大,屈服强度迅速下降;当蜂窝边长一定时,随着蜂窝厚度增加,屈服强度逐渐增加。通过有限元分析方法能有效地降低实际测试费用。     

Dynamic buffering performance of the honeycomb paperboard filled with polyurethane

A new kind of composite buffering material was made by filling the voids of honeycomb paperboard with polyurethane. Drop tests were performed to evaluate the dynamic energy absorption capacity of the material. Based on the tests results, we analyzed the mechanical behaviors of the material under different conditions and obtained the inherent influencing laws of some factors on the material＇s dynamic buffering performance. It was shown that the dynamic buffering performance varied directly with impact velocity, and inversely with the void diameter, thickness and buffeting area of the composite material.     

Optimum design of lightweight silicon carbide mirror assembly

According to the design requirement and on the basis of the principle that the thermal expansion coefficient of the support structure should match with that of the mirror, a lightweight silicon carbide primary mirror assembly was designed. Finite element analysis combined with the parameter-optimized method was used during the design. Lightweight cell and rigid rib structure were used for the mirror assembly. The static, dynamic and thermal properties of the primary mirror assembly were analyzed. It is shown that after optimization, the lightweight ratio of the silicon carbide mirror is 52.5%, and the rigidity of the silicon carbide structure is high enough to support the required mirror. When temperature changes, the deformation of the mirror surface is in proportion to the temperature difference.     

Backup roll contour of a SmartCrown tandem cold rolling mill

SmartCrown was a new system developed by VAI for improving the strip profile and flatness control first applied in 1700mm tandem cold rolling mills at Wuhan Iron & Steel (Group) Corporation (WISCO). After tracing and testing, the application of the conventional crown backup roll matching the SmartCrown work roll of the production mill led to heavy and nonuniform wear, and the edge spalling of the backup roll often occurred. A 3-dimension finite element model of roll stacks was established, which was used to analyze the above-mentioned problems, and it was found that the main reason was the highly nonuniform contact pressure distribution between the work roll and the backup roll. A new FSR (flexible shape backup roll) was developed and applied in 1700mm tandem cold rolling mills. A lot of good actual effects of FSR, such as evident improvement in profile and flatness of strips,non-occurring edge spalling, wear uniform, and remarkable decrease in roll consumption were validated by long-term industrial applications.     

波形梁护栏受侧面碰撞过程中的能量转换分析

波形梁护栏在受侧面碰撞时吸收碰撞能量的能力是衡量其安全性能的一项重要指标,为减小此碰撞事故造成的灾害损失程度,需对波形梁护栏在受侧面碰撞时的吸能能力进行研究分析.采用LS-DYNA动力学分析方法,对波形梁护栏在受侧面碰撞过程中的能量转换进行了对比分析,得出四种工况下碰撞能量的变化曲线,结果表明现有波形梁护栏的吸能能力尚有一定的提升空间,为进一步优化设计提供参考.     

基于显式有限元的轨道车辆撞击能量吸收研究

吸能装置是提高轨道车辆耐碰撞性能的关键部件.将金属切削加工技术应用到轨道车辆的被动安全防护上,提出利用切屑的生成过程吸收列车的撞击能量,作为新型吸能装置的吸能原理.建立了金属薄壁结构切削吸能过程的三维显式有限元模型,分析了刀具的前角对薄壁结构切削吸能性能的影响,并与金属薄壁结构的压缩吸能进行了比较.结果表明,金属切削吸能过程是理想的轨道车辆撞击能量吸收过程.     

复合管撞击吸能特性的数值研究

针对大变形、大应变的复合材料受撞击吸能的复杂的过程,进行了数值分析,综合了复合材料的各种失效准则,运用非线性有限元理论建立了数值分析模型．研究了外部缠有增强环氧玻璃纤维的金属圆柱管(简称为复合管)在轴向撞击载荷下的能量吸收特性,并从金属材料的性能、复合材料层的厚度和纤维的铺设角度这几个方面研究了复合管的吸能性能的影响因素,数值模拟结果与实验结果吻合,为复合材料吸能元件的设计和研究提供了有价值的参考．     

Influence of Density on Compressive Properties and Energy Absorption of Foamed Aluminum Alloy

The foamed aluminum alloys with different densities were fabricated by melt foaming technique. The compressive properties and energy absorption of the foamed aluminum alloy with different densities were analyzed. The results reveal that the compressive stress-strain curves follow the typical behavior of cellu- lar foams with three deformation stages. Under the same strain, the energy absorption capability decreases with the decrease of density. However, with increasing the strain, the energy absorption efficiency of foamed metal increases initially and then decreases. The lower the density, the longer the plateau region, within the range of high strain, the energy absorption efficiency is always high.