蔗渣包装制品模压工艺与性能分析

根据蔗渣包装制品模压的性能与质量的关系,分析了胶量、热压温度、时间和压力对蔗渣包装制品模压的物理力学性能的影响。对生产蔗渣包装制品模压工艺做了系统研究,确定了蔗渣包装制品模压的较佳工艺参数。     

蔗渣模压制品工艺研究

根据蔗渣模压制品的特性与质量的关系，分析了胶量、热压温度、时间和压力对于模压制品各项物理力学性能的影响。对蔗渣模压制品工艺做了系统研究，确定了模压制品较佳工艺参数。     

模压法制备C/C复合材料的研究

对模压法制备 Ｃ／ Ｃ复合材料的坯体模压工艺过程、 Ｃ／ Ｃ复合材料的致密化过程及 Ｃ／ Ｃ复合材料的结构和性能的相关性进行了研究。结果表明,物料中纤维含量及模压的温度、压力是影响初坯体成型及其密度的关键;除工艺条件外,原料的组成也是影响 Ｃ／ Ｃ复合材料致密化的重要因素;对 Ｃ／ Ｃ 复合材料力学性能研究的结果表明, Ｃ／ Ｃ复合材料的密度对材料的力学性能有很重要的影响。     

废旧线路板粉料/玻璃纤维增强复合材料研制

以废旧线路板回收处理过程中得到的塑料粉料与玻璃纤维作为增强材料,采用模压成型的方法制备成不饱和聚酯复合材料。研究了模压工艺参数以及废弃物粉末填料配比等对复合材料力学性能的影响规律,并初步展望了废弃物复合材料的应用。结果表明,随着模压温度、压强、模压时间和填料含量的增加,复合材料的弯曲强度先升高后降低;在优化的模压工艺参数条件下,用废弃粉体与短切玻璃纤维作为组合增强体,制得的不饱和聚酯复合材料的力学性能远大于仅用废弃粉体作为增强体的力学性能,其弯曲强度和冲击强度可达150MPa、18kJ/m2。     

正交设计确定模压条件对HDPE/CB复合材料PTC强度的影响

在塑炼方法和复合材料组成一定时,用统计学方法,设计了四因子三水平的正交实验以确定不同模压条件对HDPE/CB复合材料PTC强度的影响。结果发现,各设计因素对样品PTC强度的影响大小顺序为:冷却时间>模压温度>模压压力>模压时间。最优模压条件为:模压压力8 MPa,模压温度155℃,模压时间15 min,模压后的冷却时间40 min。在最佳模压成型工艺条件下得到的样品PTC强度为8.4,与统计学的预测结果一致,后NTC强度小于0.8。冷热循环实验结果表明HDPE/CB复合材料有良好的电阻率-温度稳定性。     

陶瓷基复合材料（SiCw／Y—TZP）在循环压应力下的疲劳裂纹扩展

研究了碳化硅晶须（ＳｉＣｗ）增强，Ｙ２Ｏ３稳定的ＺｒＯ２四方多晶体（Ｙ－ＴＺＰ）复合材料（ＳｉＣｗ／Ｙ－ＴＺＰ）在循环压应力作用下的疲劳特性，单边缺口弯曲试样在纵向循环压应力作用下缺口根部产生垂直于压应力的Ｉ型裂纹，类似于金属材料，在室温下循环应力导致Ｉ型裂纹的稳定扩展。压应力在缺口根部产生的不可逆损伤区在循环卸载过程中形成较大的残余拉伸应力场，使裂纹萌生并长大，同时，裂纹面产生的碎粒及晶须拔出导     

膨胀石墨/聚醚砜复合材料的制备及力学性能

采用微波辐射法制备了膨胀石墨(EG),将其作为增强相加入到聚醚砜(PES)基体中,利用溶液共混法和真空辅助模压成型工艺得到EG/PES复合材料,使用SEM、FTIR和XRD等分析手段表征了EG及其复合材料的微观结构和性能,并对复合材料的力学性能进行了测试。结果表明:PES分子插入到了EG片层内部,并且EG与PES分子之间产生了氢键作用;当EG含量为5.0%(质量分数)时,复合材料的拉伸和弯曲强度达到最大值,分别为94.6 MPa和146.7 MPa,较树脂基体提升了10.5%和7.3%;EG在PES基体内的分散性直接影响了复合材料的力学性能,嵌入到复合材料内部的EG不仅能够改变微观裂纹的走向,还能阻止其进一步蔓延和扩展,改善复合材料内部的应力分布情况。     

金属薄膜/复合材料结构高低温循环过程的热应力分析

分析了用于卫星天线反射器的金属薄膜/复合材料结构在模拟空间环境寿命试验的高低温循环过程中的应力;给出了金属薄膜在经历高低温循环时产生微裂纹的机理。根据微裂纹产生机理,提出了选用合适的过渡层材料在金属薄膜和复合材料基底之间形成应力释放层,抑制金属薄膜产生微裂纹。仿真分析和试验结果均证实了这一方法的可行性,并提出了进一步降低微裂纹产生的措施。     

碳纤维增强聚醚酮酮模压复合材料结构与性能调控

为探究模压工艺参数对碳纤维增强聚醚酮酮复合材料(CF/PEKK)结构与性能的影响规律,采用真空模压工艺制备CF/PEKK复合材料层压板,系统讨论了模压温度和压力对树脂与纤维的界面结构、PEKK凝聚态结构及复合材料力学性能的影响,通过扫描电镜分析了复合材料的微观结构,讨论了复合材料的失效形式,采用X射线衍射观察了复合材料中PEKK的晶体结构,使用动态热机械分析研究了复合材料界面阻尼与模压成型工艺的关系。研究结果表明,在365℃的模压温度和5.0～6.0 MPa模压压力下,CF/PEKK复合材料的综合力学性能最优,其中拉伸强度达到965 MPa,弯曲强度849 MPa,层间剪切强度59 MPa,复合材料的断裂失效形式以树脂开裂与层间Z形断裂为主。     

氮化硼纳米管增强氮化硅陶瓷裂纹扩展的有限元分析

在氮化硅(Si3N4)陶瓷中添加氮化硼纳米管(BNNT)增强体制备了BNNT/Si3N4复合材料,利用三点弯曲强度及单边切口梁(SENB)法测定了BNNT/Si3N4复合材料的弯曲强度和断裂韧性。通过SEM观察了BNNT/Si3N4复合材料的微观形貌。利用ABAQUS有限元模拟了BNNT/Si3N4复合材料中裂纹偏转、钉扎、分叉、桥联尖端的应力分布情况。结果表明:BNNT/Si3N4复合材料的弯曲强度和断裂韧性明显高于Si3N4陶瓷,说明BNNT对Si3N4陶瓷的裂纹扩展有阻碍作用。Si3N4陶瓷与BNNT的界面结合良好,而良好的结合界面有利于提高界面的摩擦力。BNNT/Si3N4复合材料裂纹扩展情况的有限元模拟表明,BNNT可以吸收Si3N4陶瓷裂纹尖端的应力,有效阻止了Si3N4陶瓷基体中产生大的应力集中,而且当裂纹扩展到BNNT附近时,裂纹尖端会形成强的应力屏蔽区,增加了裂纹扩展的阻力。裂纹钉扎、桥联对增加裂纹扩展阻力的作用高于裂纹偏转和分叉。     

Damage in composite laminates: Effects of transverse cracks

Two different methods of solution are used to study the effects of transverse cracks in cross-ply composite laminates. The results of an approximate analytical solution are compared with those obtained using a finite element analysis in order to study the effects of transverse cracks on the degradation of elastic and thermal coefficients as well as stress distributions. In particular, it is shown that transverse cracks cause significant degradation of the Poisson's ratio and shear modulus of the laminates, and also affect some stress distributions in a peculiar manner. Theoretical results are compared with existing experimental results where appropriate.     

吊灯灯罩缓冲衬垫的随机振动仿真分析及实验验证

目的研究吊灯灯罩纤维模塑缓冲衬垫在随机振动激励下结构设计的合理性,及其对产品的保护性能。方法利用Ansys软件对吊灯灯罩纤维模塑缓冲衬垫包装件进行模态分析,获取包装件的固有频率和振型,将路面随机振动激励谱作用于纤维模塑缓冲衬垫包装件进行仿真分析,得到包装件的应力、应变云图和加速度功率谱密度响应曲线等,以此分析其结构设计的合理性以及对产品的保护性能,并进行实验验证。结果灯罩所受应力值远小于灯罩材料所能承受的最大屈服应力值(75 MPa),吊灯灯罩保存完好;有限元分析得到的结果与实测结果一致。结论纤维模塑缓冲垫结构设计合理,强度可满足保护产品的要求;利用有限元仿真分析解决纤维模塑缓冲包装制品的随机振动问题是可靠的,适用于动态环境下同类缓冲制品性能的研究,为缓冲包装产品性能预测、结构设计及优化提供有效分析手段。     

Thermal stresses in a laminate composite with infinite row of parallel cracks normal to the interfaces

Under the assumption of plane strain, some linear thermoelastic problems concerning a laminate composite containing an infinite row of parallel cracks situated normal to the bond lines are solved by the use of integral transform technique. The thermal stresses are caused by a uniform heat flow disturbed by the presence of the cracks and the interfaces. The problem is reduced to that of solving a Fredholm integral equation of the second kind which is solved numerically by the use of Gaussian quadrature formulas. The effect of various quantities of physical interest on the stress intensity factor is shown graphically.Calculations are also carried out for the stress intensity factor for a laminate composite with a crack normal to the interfaces. This is accomplished by taking the limiting case of a laminate composite with an infinite row of parallel cracks normal to the interfaces.     

基于厚度变化的纸浆模塑模内干燥特性研究

目的 探究模内干燥纸浆模塑制品厚度变化规律及干燥特性。方法 使用纸浆模塑成型机在不同干燥温度下，对3种不同初始厚度的纸浆模塑制品进行热压干燥实验，对实验所得产品的厚度变化和质量变化数据进行分析，并绘制干燥特性曲线。结果 纸浆模塑制品热压干燥过程可分为预压阶段、恒速干燥阶段和降速干燥阶段3个过程。在预压阶段，蓬松的纸浆模塑湿坯被模具挤压致密，厚度值出现瞬时减薄的趋势，减厚率高达40%以上，在恒速及降速阶段厚度则会逐步递减至一个平衡值。结论 根据实验结果获得了基于厚度变化的纸浆模塑制品的干燥特性。     

VARI工艺成型纤维增强树脂复合材料层合板厚度和纤维体积分数的影响因素

分析了影响真空辅助成型技术（VARI）工艺成型复合材料的纤维体积分数和厚度均匀性的关键因素,即VARI成型工艺的树脂流动控制形式、纤维预制体状态、织物状态、树脂黏度,通过试验分析了各因素对VARI成型复合材料厚度和纤维体积分数的影响。试验结果表明,采用HFVI（high fiber-volume vacuum infusion）工艺、BA9914树脂及真空处理后的U3160单向机织物成型的纤维增强树脂复合材料层合板,其纤维体积分数和厚度均匀性能够接近预浸料/热压罐成型的复合材料制件的水平。     

Effect of gate size on the melt filling behavior and residual stress of injection molded parts

This paper studies the effects of gate size on the cavity filling pattern and residual stress of injection molded parts. A total of three rectangular gates with different sizes were used. Experiments were carried out by using a dynamic visualization system. A flow visualization mold was specially designed and made for this study. A high-speed video camera was used to record the mold filling phenomena of cavities with different gate size and different processing parameters. In addition, a Stress Viewer was used to characterize the residual stress of molded samples. It was found that the undersized gate has many adverse effects on the filling behavior and residual stress of molded parts. With a larger gate, the cavity will be filled faster and residual stress of parts may be smaller. The result of the study also indicates that nozzle temperature and injection rate can significantly affect the above two aspects.     

Effect of transverse cracks on the elastic properties of high temperature angle-ply laminated composites

The development of transverse cracks can be detrimental to the stiffness and dimensional stability of composite laminates. In this investigation, a modified shear lag analysis, taking into account the concept of stress perturbation function, is employed to evaluate the effect of transverse cracks on the stiffness reduction in high temperature angle-ply laminated composites. The results present well the effect of high temperature and the fibre orientation of the outer layers on the degradation of mechanical properties of the angle-ply polymer composite laminates.     

Effect of strain rate on cushioning properties of molded pulp products

Molded pulp product is widely used in distribution chains as a cushioning packaging of industrial products due to its favorable cushioning capability. How to evaluate the cushioning capability of molded pulp product is the key issue many scholars are interesting in. The load carrying capacity and energy absorbing of the molded pulp products used in the cushion packaging of mobile phones both in the static compression and dynamic impact were investigated in this paper by applying the experiment and finite element analysis. The static compression was conducted with the compression speed of 12 mm/min corresponding to the nominal strain rate 3.8 × 10⁻³ s⁻¹, and the dynamic impact tests were conducted with three drop heights of 25, 50 and 80 cm corresponding respectively to the nominal strain rates 4.2 × 10¹, 6.0 × 10¹ and 7.5 × 10¹ s⁻¹. The high speed camera was used to record the dynamic impact process and deformation. The finite element model of molded pulp product was built, and the stress and displacement nephograms, the dynamic impact deformation process, the load–displacement curve and the energy absorption curve of the molded pulp product were archived. The comparison between the finite element analysis and the experiment was made. The load–displacement curve of the finite element analysis is in agreement with that of the experiment in the static compression, and the energy absorption curves of the finite element analysis with different nominal strain rates are in agreement with that of the experiment in the area of the point of optimum energy absorption. However, a growing gap between the finite element analysis and the experiment appears with the nominal strain rate increasing, which may be induced by the use of the static stress–strain curve of the material in the finite element analysis of dynamic impact. The molded pulp product experiences the process from structural deformation, local stress concentration, first local buckling, redistribution of stress, global buckling, to structural dilapidation and densification. Two obvious buckling processes occur because of its complicated structure and two layers in structure. However, some additional local buckling also occur before the global buckling of structure in the case of dynamic impact with higher nominal strain rate. The deformation processes of molded pulp product from the finite element analysis and the experiment recorded by high-speed camera are coincident. With the nominal strain rate increasing, the yield stress of molded pulp product increases obviously, and the shoulder point of the energy absorption curve moves upward to the right. The yield stress under the dynamic impact at a drop height of 80 cm increases 59.4% compared with that under the static compression, and the corresponding optimum energy absorption increases 85.4%. The effects of strain rate on the load carrying capacity and the energy absorption of molded pulp product are remarkable. The results can be applied to the design of molded pulp products.     

纸浆模塑制品印刷适性分析

纸浆模塑制品因其颜色单一限制了它作为装饰材料的应用范围。对纸浆模塑制品的印刷适性进行了深入探析,选定了丝网印刷方式对其进行装潢印刷,比较了不同丝网目数下溶剂型油墨和UV油墨的印刷效果,找出了最优丝网印刷工艺参数,为纸浆模塑制品的装潢印刷提供了技术参考,以便能够拓展纸浆模塑装饰材料的应用范围和市场空间。     

聚合物注塑内应力和翘曲变形的数值模拟

由聚合物粘弹性理论和注塑成型原理出发,考虑了聚合物玻璃态的非线性粘弹性响应,采用新的四元件粘弹性力学模型模拟计算注塑制品冷却过程中内应力的形成与发展。在此基础上,采用改进的Allman膜单元[1]和离散Kirchhoff板单元[2]组合生成的板壳单元,模拟计算注塑件的翘曲变形,计算结果与实验结果一致,计算精度有所提高。