根据防护要求和防护机制,设计了一种C/C-SiC陶瓷/铝基复合泡沫复合装甲.在确保复合装甲面密度为44kg/m2的前提下,以弹击后剩余弯曲强度为评价标准,以陶瓷板布置位置、各组成层厚度、泡沫金属中泡沫孔径尺寸为研究因素,设计了三因素三水平的正交模拟优化方案,利用有限元软件ABAQUS模拟了子弹侵彻陶瓷靶板的过程及弹击损伤后复合装甲的弯曲实验过程,预测了剩余弯曲强度,并进行了结构优化.根据数值模拟结果制备陶瓷复合装甲试样,进行实弹打靶和弯曲实验以验证复合装甲试样剩余弯曲强度.结果表明,以MIL-A-46103E Ⅲ类2A级为防护标准,剩余弯曲强度最高的陶瓷复合装甲最优化结构形式为:陶瓷板厚度12mm、陶瓷板做防弹面板、Al基复合泡沫孔径为4mm+10mm的混合;对剩余弯曲强度的主次影响因素排序为:陶瓷板厚度＞陶瓷板布置位置＞Al基复合泡沫孔径.

针对水泥窑余热发电锅炉受热部件的结渣结垢问题,提出采用先驱体法制备陶瓷防护涂层.高温环境抗玷污试验表明,先驱体法制备的金属基聚硅氮烷陶瓷涂层具有良好的抗Na2S04和水泥飞灰高温结垢性能,可在水泥窑余热发电锅炉的工作温度环境中发挥作用.

构建了轴承-轴悬臂梁耦合能量阱模型,利用线性刚度元件的几何特性产生非线性恢复力,构造了具有双稳态的非线性能量阱(BNES).利用劳斯-赫尔维茨法则对非线性能量阱(NES)平衡点的稳定性进行了分析,通过数值算法分析了BNES对轴的振动抑制性能,基于能量传递率对比了不同激励强度下BNES的减振性能,结合势能函数分析了非线性刚度比和势阱深度的关系,揭示了非线性刚度比对触发阈值的影响.结果表明:BNES存在1个不稳定平衡点和2个稳定平衡点;相比于普通NES,BNES在低扰动下减振性能更好,在触发阈值附近能量传递率最高,且随着非线性刚度的增加,触发阈值降低.

In this paper, the ballistic damage mechanism and residual bearing capacity of ceramic/backing plate armor were investigated. First, a series of lightweight armors were prepared, consisting of ceramic and ultra-high molecular weight polyethylene fiber-reinforced resin matrix composite (UHMWPE) plates, and were wrapped in a high-strength fabric. Then, the ceramic/UHMWPE armors were hit by one or two bullets, and finally subjected to compression testing. The results showed that the main failure mode of integral ceramic/UHMWPE armors was ceramic brittle fracture. Many zigzag patterns on the compression curve indicated that the specimens had undergone the stages of crack propagation, ceramic fragment reorganization, plastic deformation of UHMWPE backing plate, interlaminar tearing, and overall fracture. The failure of spliced ceramic/UHMWPE armors was mainly due to the dislocation between ceramic sheets; the smooth compression curves indicated that there was no recombination of ceramic fragments and obvious interlayer debonding during the compression. Under the maximum load, each ceramic/UHMWPE armor with ballistic damage did not suddenly break and fail. The structure and thickness of ceramic plates all had an impact on residual strength: under the same structure, the greater the thickness, the greater the residual strength, but the relationship between them was not linear; under the same thickness, the residual strength of the spliced ceramic/UHMWPE armor was higher. The residual strength was also related to the number of shots: after two bullets hit, its value was only one-third of that after one bullet hit.

C/C-SiC composites were prepared by precursor transformation method. The microstructure and properties of the samples were analyzed. The effects of silicon infiltration temperature, holding time, vacuum degree and cracking cycle on the density of C/C-SiC composite were studied. The results show that with the increase of siliconizing temperature, the density of the material increases at first, and then decreases rapidly. With the increase of heat preservation time, the density of the material increases rapidly at first, keeps stable for a period of time and then decreases slowly. With the increase of sintering vacuum, degree, the density of the material increases rapidly. With the increase of cracking cycle, the density of the material increases continuously, but the growth rate decreases gradually. After 11 cycles of “impregnation curing cracking” process, the C/C-SiC composite prepared obtained a maximum density of 2.09 g/cm3 and a minimum porosity of 7.6%. At this time, it also has the most excellent comprehensive mechanical properties: bending strength of 468 MPa, tensile strength of 242 MPa, fracture toughness of 19.6 MPa·m1/2 and Vickers hardness of 17.2 GPa.

采用真空铜模吸铸技术制备了尺寸为Φ5 mm×90 mm的Ti-45A1-8.SNb-(W,B,Y)(at.％)合金棒状试样,研究了急冷快速凝固显微组织演化及凝固路径.结果 表明:基于Ti-A1-8.5Nb三元合金系的变温截面图与铸态凝固组织特征,该铸态合金凝固路径是单一β相凝固,初生相为β相,其主要相组成为α2相、γ相及B2相以及少量硼化物和氧化钇颗粒;与铸态相比,表面急冷区凝固组织具有明显的单一β相凝固特征,而糊状区枝晶形貌明显且存在包晶晕,为典型的包晶凝固,从急冷区至糊状区,其凝固方式由单一β相凝固向包晶凝固转变;在表面急冷区,脉络状B2相、针状硼化物、氧化钇颗粒以及片层结构(α2+γ)的形成一定程度上被抑制,随着冷却速率的提高,α2相(002)和γ相(111)面的衍射峰向高角度偏移约0.6°.

挺杆是汽车发动机配气机构的重要组成部分.它属于薄壁类零件,在最后的磨削过程中极易发生变形.现有的加工方法很难保证其尺寸公差和形位公差的要求.设计了一种全新的浮动薄膜夹具.该夹具在挺杆底端采用硬点支撑、在口端采用浮动支撑,可实现端面和内径表面的复合磨削.最终能保证零件的尺寸公差和形位公差.

Based on the bulletproof mechanism of ceramic composite armor, structural design and numerical simulation optimization of SiC/UHMWPE fiber composite armor were carried out to satisfy the protection requirements of vehicle. Penetration depth of bullet was taken as the evaluation standard, and the thickness, shape, size, and layout of SiC wood ceramic bullet proof sheet were considered as the research factors. An orthogonal simulation optimization scheme of four factors and three levels were designed, when the surface density of ceramic composite armor was 38 kg/m(2). Bulletproof performance was simulated by ANSYS/LS-DYNA finite element software. The optimized size parameters owing to the minimal penetration depth of bullet were selected. Accordingly, a SiC wood ceramic composite armor was prepared, and the bulletproof performance of designed ceramic composite armor was up to the protection standard of NATO AEP-55 STANAG 4569 level II as determined by the real bullet shooting test. Results show that the designed structure has 8 mm-thick SiC wood ceramic bulletproof panel and 13.7 mm-thick UHMWPE fiber bulletproof panel. The bulletproof panel is made of 4900 mm(2) hexagonal SiC wood ceramic bulletproof sheets. The influencing factors of SiC wood ceramic bulletproof sheet on the bulletproof performance is as follows: arrangement position>thickness>size>shape.

为了合理地展示知识结构,避免微课资源分散无序、聚合度低等问题,文章利用知识元组织模型的概念,对《汽车构造》微课的课程体系进行了重构,从教学目标、微课分类、知识元主题构建、评价体系重构和辅助资源库建设等部分入手对微课进行了设计,实现了微课资源的深度聚合.学生通过微课的学习,提高了获取知识的效率,取得良好的学习效果.

OBE教学模式是一种成果导向教育,是一种先进的教育理念,是高等工程教育改革的正确方向.根据我校过程装备与控制工程专业的培养方案,针对《机械工程材料》课程中存在的重点问题,制定了合理的教学目标,整合教学资源,融入思政元素.并对考核方式进行了改革,体现学生在教学过程中的主体地位.将教学结果和学生能力的培养作为核心,增进学生在学习过程中的创新意识,提高学生解决复杂问题的能力.

以师资队伍建设和应用型大学建设要求为契机,把教师工程实践、挂职锻炼基地建设成为优秀的学生校外实习基地,即建立"实践实习基地一体化"教学模式,为有效、高效、实效地培养应用型人才提供实施场所,教师的专业指导能力同步提高.

碳纤维增强SiC(C/SiC)陶瓷基复合材料不仅具有耐高温、高比强、高比模、耐腐蚀、耐磨损和低密度的特点,还具有良好的高温力学性能,目前,已成功用于第三代航空发动机、冲压发动机、固体和液体发动机的热结构,以及空天飞行器防热结构等方面.界面相是碳纤维增强SiC陶瓷基复合材料极其关键的显微组织结构,其可视为坚固的“桥梁”,不仅连接增强体和基体,也传递二者之间的应力,对C/SiC复合材料综合力学性能起到非常关键的作用.本文主要简述了C/SiC陶瓷基复合材料界面相研究状况,包括界面相的功能、类型、制备方法及对力学性能的影响.

陶瓷复合装甲是防弹车辆的热门防弹方案,根据轻型防弹车辆防护要求,进行拼接式陶瓷复合装甲结构设计,通过有限元软件ANSYS/LS-DYNA模拟陶瓷片形状和尺寸对复合装甲防弹性能影响,并进行打靶试验验证,结果表明所提出的数值模拟计算方法能较好模拟子弹对拼接式陶瓷复合装甲的侵彻过程,相同形状的陶瓷片,面积较大陶瓷片的防弹性能要优于面积较小陶瓷片的防弹性能;正六边形陶瓷片的防弹性能要优于相同面积的正四边形陶瓷片的防弹性能.

基于高层建筑区救援工作的特殊性,结合常用升降机构的结构特点,设计微型逃生电动车用升降装置.主要由支撑底座、液压支撑臂、剪叉机构、顶部救援平台组成,可实现快速启动升降、平稳制动和自由频繁换向.使用CATIA进行三维建模,利用有限元分析软件ANSYS对装置动态稳定性进行校核计算,装置的性能满足设计和使用要求.

<span id="ChDivSummary" name="ChDivSummary" class="abstract-text">以消除回转式烘干机筒体内气流"短路"形成"风洞"的问题,基于对扬料板结构参数、安装参数以及工艺参数的分析和数值计算结果,开发回转式烘干机整体参数可视化优化分析软件。该软件以烘干机和扬料板的几何参数为输入,以获得瀑落料幕均匀性和最大撒落物料量为目标,以扬料板安装参数实时计算、终止和起始扬料角优化、扬料板升举量和数量计算三个模块分别显示计算和优化结果,结合生产中扬料板的常用几何参数,并根据整体优化结果,组合出两种方案六组最佳匹配参数,终止扬料角可达270°,为回转式烘干机的在不同转速、不同要求下的设计及改造提供理论依据。</span>

针对《机械工程材料》课程当前存在的突出问题,对教学内容、教学方法的优化进行探索,以建立一种高效的教学结构模式,培养出实践能力强的应用型人才.

研究了温度和各成分的质量比对聚碳硅烷/二乙烯基苯和聚碳硅烷/二乙烯基苯/二甲苯先驱体溶液黏度的影响,以及质量比对其二者先驱体交联率和陶瓷产率的影响.结果表明:聚碳硅烷/二乙烯基苯先驱体的溶液黏度随温度的升高而降低;提高二乙烯基苯的含量,可以降低先驱体的溶液黏度,改善流动性,但是会降低先驱体的交联率和陶瓷产率.聚碳硅烷/二乙烯基苯/二甲苯先驱体的溶液黏度随温度升高而逐渐降低;增加二甲苯的质量比,先驱体溶液的黏度明显降低,流动性增加;且在40～60℃范围内,当聚碳硅烷/二乙烯基苯/二甲苯质量比为10:3:2时,先驱体的溶液黏度在170～410 mPa·s之间,具有良好的流动性、长时间稳定性以及较高的交联率和陶瓷产率,适宜作为碳纤维预制体的浸渍液.

航空激光产品对密封性能有严格要求,密封性能的优劣将直接影响航空激光产品的性能与使用寿命.基于航空激光产品密封设计缺少理论指导的现状,通过调研、试验和理论研究,从密封件选材、构型选择、沟槽尺寸确定、密封螺钉排布四个方面提出航空激光产品密封设计的原则和依据,并从固定螺钉装配和密封件装配两个方面总结航空激光产品密封结构的装配工艺,可以为提高航空激光产品的密封可靠性提供参考.

为了研究纤维束内沥青炭和粗糙层热解炭的力学性能,以2.5D针刺炭毡为增强体,分别通过中温煤沥青浸渍炭化和化学气相沉积制备得到C/C复合材料.使用G200型纳米压痕仪对C/C复合材料纤维束内基体进行纳米压痕测试,采用连续刚度测试方法,利用Oliver和Pharr模型获得试样弹性模量随测试深度的变化,利用弹性模量和硬度两参数Weibull分布函数对纳米压痕测试结果进行统计分析.结果表明,沥青炭和粗糙层热解炭的弹性模量平均值分别为(14.92±2.02)GPa和(12.87±1.35)GPa;硬度的平均值分别为(0.64±0.14)GPa和(0.67±0.17)GPa.沥青炭和粗糙层热解炭的弹性模量的Weibull分布模数分别为8.60和9.18,弹性模量的特征值分别为15.63 GPa和13.40 GPa.