组合瓦楞纸板缓冲衬垫的力学性能研究

本文研究了3A型、3B型、BAB型组合瓦楞纸板缓冲衬垫的抗弯性能和平压性能。抗弯试验结果表明，组合衬垫的载荷一挠度曲线可分为4个阶段，依次为瞬时弹性变形阶段、延迟弹性变形阶段、弹塑性变形阶段和屈服塑性变形阶段；从抗弯性能方面考虑，在对瓦楞纸板进行粘接使用时，可以将A型或B型瓦楞自行组合，但最好不要将B型或A型瓦楞与AB型瓦楞组合。平压试验结果表明，在3A型、3B型及BAB型组合瓦楞纸板缓冲衬垫的静态压缩曲线均存在三个峰值，且峰值与瓦楞纸板层数一一对应，各层按照屈服强度从小到大的顺序依次屈服、破坏；从静态压缩性能方面考虑，BAB结构的抗压性能最好，3B结构次之，3A结构最差。根据静态压缩试验绘制的瓦楞纸板缓冲系数-最大静应力曲线，为采用组合瓦楞纸板衬垫进行缓冲包装设计提供了依据。当采用该曲线进行缓冲包装时，应根据产品特性及流通环境特点，尤其是产品或包装件可能给予缓冲衬垫的静压力范围，合理选择衬垫的组合型式。     

瓦楞纸板的静态压缩非线性模型

分析了瓦楞纸板压缩性能的基本特征，对多种瓦楞纸板进行了测试，应用弹塑性理论，建立了瓦楞纸板的平压、边压和侧压的静态应力应变数学模型，根据少量实测数据，识别模型参数。     

压捆机压缩特性测试方法的分析

为研究牧草、秸杆等物料的压缩特性，以9KG350型高密度压捆机为试验装置，根据该机的结构特点和压缩特性的基本参数选用了压力传感器和位移传感器，着重介绍了其测试原理和方法，并通过试验结果表明了该测试系统的性能和可靠性。     

压捆机压缩特性测试方法的分析

为研究牧草，秸秆等物料的压缩特性，以９ＫＧ－３５０型高密度压捆机为试验装置，根据该机的结构特点和压缩特性的基本参数选用了压力传感器和位移电感器，着重介绍了其测试原理和方法，并通过试验结果表明了该测试系统的性能和可靠性。     

纸瓦楞夹层板的压缩变形与塑性吸能特性研究

目的研究在不同压缩速率下纸瓦楞夹层板的压缩变形与塑性吸能特性。方法利用Hoff夹层板、正交各向异性弹性薄板理论和工程梁理论,研究瓦楞夹层板的横向压缩位移,分析瓦楞芯层的压缩变形模式及塑性吸能特性,提出芯层结构的压溃强度模型,并通过静态压缩实验进行对比分析。结果B型、C型纸瓦楞夹层板的压溃强度理论预测值分别为0.1195,0.0612 MPa,在1,12,18,48 mm/min的压缩速率下,B型纸瓦楞夹层板的压溃强度分别为0.1011,0.1071,0.1048,0.1075 MPa,C型纸瓦楞夹层板的压溃强度分别为0.0462,0.0640,0.0475,0.0451 MPa。结论低应变率(低压缩率)条件下,纸瓦楞夹层板的横向压缩性能影响基本不变,弹性强度、屈服强度、压溃强度等基本相同。对于相同的材质,几何参数对纸瓦楞夹层板的压缩性能和塑性吸能影响较大。     

芯子开槽对蜂窝纸板平压强度的影响

在试验的基础上，研究了芯子开槽后蜂窝纸板平压强度的变化情况，并得到了蜂窝纸板的压缩特性曲线。试验结果表明，芯子的一侧均匀开槽后的蜂窝纸板，其平压强度较未开槽的蜂窝纸板的平压强度高。     

立式瓦楞复合纸板静态压缩试验与有限元分析

目的对立式瓦楞复合纸板的静态压缩过程进行试验研究和有限元分析,研究不同楞型立式瓦楞复合纸板的力学性能。方法制作A楞、AB楞、B楞等3种不同立式瓦楞复合纸板试样,进行静态压缩实验,得到其压缩应力-应变曲线;建立3种楞型的立式瓦楞复合纸板有限元模型,进行静力学分析,得到其压缩应力-应变曲线,并与实验结果进行对比分析。结果试验和有限元分析均显示立式瓦楞复合纸板的静态压缩过程与蜂窝纸板的静态压缩过程类似,包括弹性阶段、屈服阶段、平台阶段、密实化阶段,试验和有限元分析所得到的压缩应力-应变曲线相吻合。纸板的峰值应力和平台应力与楞型有关,且随着楞高的增大而减小。结论通过试验研究和有限元分析方法得到了不同楞型立式瓦楞复合纸板的静态压缩性能,对该新型材料的应用有重要参考价值。     

音频信号的动态效果处理插件（一）

音频信号的动态处理有压缩和扩展2种基本模式,文中将具体介绍其工作原理,以及高电平压缩、整体压缩、响度增强压限、软削顶处理等效果处理的应用和操作方法。     

层合瓦楞纸板三向静态平压性能研究

通过静态压缩试验,对B楞和C楞层合瓦楞纸板X,Y,Z3个方向的平压性能进行了研究,并绘制了其载荷-变形曲线和应力-应变曲线。纸板的载荷-变形曲线表明：压缩时各纸板3个方向的曲线走势类似,都有一段线性变形部分,当载荷达到最大值后,X向和Z向的曲线呈波浪状下降,而Y向的曲线近似于水平波动。纸板的应力-应变曲线表明：3个方向的压缩中,Z向的压缩强度值最大,X向次之,Y向最低,Z向值为X向的3～6倍,为Y向的12～14倍。此外还对瓦楞纸板平压强度与Y向压缩强度的关系和瓦楞纸板边压强度与Z向压缩强度的关系进行了分析。     

不同组合角度瓦楞纸板缓冲性能研究

以不同组合角度的瓦楞纸板为研究对象,以角度为变化参数,结合matlab软件进行分析研究。通过边压强度、平压强度试验,拟合得到了其强度与组合角度的关系模型,精度、误差在允许的范围内;通过静态压缩试验,获得了其静态缓冲系数-应力曲线。实验结果表明:瓦楞纸板的边压强度随着组合角度的增加而逐渐减小;平压强度则在组合角度为0时最大,90°,30°和45°时依次减小;静态压缩试验中组合角度为0的缓冲能力最大。     

Numerical and Experimental Investigations on Deep Drawing of G1151 Carbon Fiber Woven Composites

This study proposes to simulate the deep drawing on carbon woven composites in order to reduce the manufacturing cost and waste of composite material during the stamping process, The multi-scale anisotropic approach of woven composite was used to develop a finite element model for simulating the orientation of fibers accurately and predicting the deformation of composite during mechanical tests and forming process. The proposed experimental investigation for bias test and hemispherical deep drawing process is investigated in the G1151 Interlock. The mechanical properties of carbon fiber have great influence on the deformation of carbon fiber composites. In this study, shear angle–displacement curves and shear load–shear angle curves were obtained from a bias extension test. Deep drawing experiments and simulation were conducted, and the shear load–displacement curves under different forming depths and shear angle–displacement curves were obtained. The results showed that the compression and shear between fibers bundles were the main deformation mechanism of carbon fiber woven composite, as well as the maximum shear angle for the composites with G1151 woven fiber was 58°. In addition, during the drawing process, it has been found that the forming depth has a significant influence on the drawing force. It increases rapidly with the increasing of forming depth. In this approach the suitable forming depth deep drawing of the sheet carbon fiber woven composite was approximately 45 mm.     

野燕麦主芒纤维细胞吸湿变形的力学分析

以野燕麦主芒的厚壁纤维细胞为对象,根据其微观组织结构,建立各向异性的纤维缠绕圆管状体力学模型,导出纤维细胞在湿度载荷作用下的本构关系,分析微纤丝角、壁厚和湿度条件对应变和应力分布的影响。结果表明,纤维缠绕结构在湿度变化时的各向异性膨胀将引起管状体的轴向伸长和环向扭转,通过比较这些变形与微纤丝角之间的关系,发现微纤丝角范围为60°~80°时管状体具有稳定的变形能力。     

一种纸浆模塑蜂窝板材缓冲性能的研究

目的 为了解决因技术水平制约,纸蜂窝材料芯纸构型单一、单层厚度受限等瓶颈问题,开发一种通用型缓冲结构板材。方法 以纸浆模塑为原材料,以六棱柱结构为例,设计并加工出一种通过正反插方式组合而成的蜂窝板材,并采用有限元方法进行仿真,得到关键结构参数和相关最优参数组合。结果 正反插结构的纸浆模塑板材具有较好的耦合效应,承载能力相较于单层板材大幅提高;结合极限载荷、比吸能等评价指标对板材性能进行定量分析,初始压缩载荷最大可达到73.7kN,满足托盘等重型包装器具的承载需求。通过极差和方差分析可知,各结构参数对板材承载性能和缓冲性能的影响程度,研究表明单元壁厚、中截面边长对该板材承载性能和缓冲性能影响显著。结论 正反插结构解决了现有纸蜂窝材料高度、厚度受限,构型单一等瓶颈问题,提高了纸浆模塑蜂窝板材的承载性能和缓冲性能,可以满足重载要求。与之相关的其他正多边形锥形薄壁管单元亦可以使用同样的正反插设计理念和研究方法。     

基于Ansys的双A型瓦楞纸板稳定性分析

目的基于Ansys研究大中型运输包装堆码过程中纸质外围框的双A型瓦楞纸板失稳问题。方法使用Ansys软件并结合APDL语言构建双A型瓦楞纸板有限元模型,然后对该模型进行特征值屈曲分析,得到使纸板发生屈曲的最小临界载荷和屈曲后纸板的变形情况,最后改变纸板的高度与长度,再进行多次特征值屈曲分析,分析纸板的高度和长度与纸板临界屈曲载荷的关系。结果纸板的临界屈曲载荷与纸板的长度成正比,与纸板高度的平方成反比。结论纸质外围框双A型瓦楞纸板更加适合包装高度较低的产品,以减少失稳的可能性,当双A瓦楞纸板所承受的力大于临界屈曲载荷时,可以在瓦楞纸板的外表面添加胶合板加强筋,承担一部分的承载压力,从而使瓦楞受力在临界屈曲载荷之下。     

Damage Constitutive Equations and its Application to Fiber Reinforced Composites under Transverse Impact

Two continuous field variables, called as continuity tensor and damage variable tensor, are used to describe the anisotropic responses of an elastic-brittle material under transverse impact load. Based on the continuum damage mechanics, anisotropic damage constitutive equations in both full and incremental forms are proposed here. The expressions of effective elastic module tensor, damage variable tensor and damage propagation force tensor are further derived, and the methods for determining the tensors are explained in detail. An example of strain and damage response of a fiber reinforced composite laminated plate under transverse impact load is employed to demonstrate the application of this theory. In the example, the damage variable coupled with geometric large deformation of laminated plate is also considered. The calculating results illustrate the influence of damage on strain field in the impacted laminated plate.     

考虑双拉耦合的复合材料编织物各向异性超弹性本构模型

为了准确描述复合材料编织物的各向异性力学特性,首先,基于纤维增强复合材料连续介质力学理论提出了一种考虑纤维双拉耦合的复合材料编织物各向异性超弹性本构模型,该模型中单位体积的应变能被解耦为便于参数识别的纤维拉伸变形能、双拉耦合引起的挤压变形能和纤维间角度变化产生的剪切变形能;然后,给出了模型参数的确定方法,并通过拟合单轴拉伸、双轴拉伸和镜框剪切实验数据得到了本构模型参数;最后,利用该模型对双轴拉伸和镜框剪切实验进行了数值仿真,并将模拟结果与实验结果对比分析。结果表明:提出的本构模型适用于表征复合材料编织物在成型过程中由于大变形引起的非线性各向异性力学行为。所得结论表明提出的本构模型具有简单、实用的优点,且材料参数容易确定,可为复合材料编织物成型的数值模拟和工艺优化奠定理论基础。     

聚乙烯醇纤维改性高延性混凝土双面剪切试验及剪切韧性评价方法

为研究高延性混凝土（HDC）的剪切性能并评价其剪切韧性,设计了5组HDC试件、1组HDC基体试件（不含纤维）和1组普通混凝土对比试件,通过双面剪切试验,以纤维体积分数和HDC抗压强度为参数,分析其破坏形态、抗剪强度及峰值变形,根据试验结果提出了HDC的剪切韧性评价方法。结果表明:HDC纤维桥联作用及纤维拔出过程中吸收了大量能量,试件发生具有延性特征的剪切破坏;与基体试件和普通混凝土试件相比,HDC试件的抗剪强度和峰值变形均显著提高,其提高幅度随纤维体积分数的增加而增大;随HDC抗压强度的增大,试件抗剪强度增大,峰值变形降低;采用初始能量密度和残余剪切韧度比评价HDC的剪切韧性,其剪切韧性显著高于基体和普通混凝土。      

混合废纸纤维对发泡缓冲包装材料性能的影响

目的 研究废箱板纸和数字印刷废纸混合比例对发泡材料各项性能的影响,确定最佳纤维混合比例。方法 以废箱板纸和数字印刷废纸为主要原料,通过微波发泡法制备了一种废纸纤维发泡材料,通过微距镜头及扫描电镜对发泡材料微观结构进行观察。结果 研究表明,当废箱板纸纤维和数字印刷废纸纤维质量比为12.5∶2.5时,得到的材料综合性能最优,其密度为0.112 g/cm³、发泡倍率为1.728、变形能为6.463×10⁴J/m³、缓冲系数为5.922。结论 将2种废纸纤维混合起来所制备的发泡材料具有低密度、高发泡倍率和较好的缓冲性能。     

Investigation into the Fiber Orientation Effect on the Formability of GLARE Materials in the Stamp Forming Process

Glass-reinforced aluminum laminate (GLARE) is a new class of fiber metal laminates (FMLs) which has the advantages such as high tensile strength, outstanding fatigue, impact resistance, and excellent corrosion properties. GLARE has been extensively applied in advanced aerospace and automobile industries. However, the deformation behavior of the glass fiber during forming must be studied to the benefits of the good-quality part we form. In this research, we focus on the effect of fiber layer orientation on the GLARE laminate formability in stamp forming process. Experimental and numerical analysis of stamping a hemisphere part in different fiber orientation is investigated. The results indicate that unidirectional and multi-directional fiber in the middle layer make a significant effect on the thinning and also surface forming quality of the three layer sheet. Furthermore, the stress-strain distribution of the aluminum alloy and the unique anisotropic property of the fiber layer exhibit that fiber layer orientation can also affect the forming depths as well as the fracture modes of the laminate. According to the obtained results, it is revealed that multi-directional fiber layers are a good alternative compared to the unidirectional fibers especially when a better formability is the purpose.     

Investigation of the damage evolution of metal inserts embedded in carbon fiber reinforced plastic by means of computed tomography and acoustic emission

Carbon fiber reinforced plastics are promising materials for lightweight structures, for instance in automotive applications due to their outstanding specific mechanical properties. However, the load transfer in structural carbon fiber reinforced plastics parts via a detachable connection poses a challenge for the composite. Conventionally, the parts have to be drilled for this purpose whereby the fiber continuity is interrupted and hence the associated local stress accumulation decreases the load bearing capacity of the composite. This can be prevented by using embedded metal elements, so‐called inserts, for joining parts in structures. The damage behavior under tensile loading of inserts turned out to be extremely complex and is based on different mechanisms. In order to understand the damage evolution under tensile loading detailed knowledge about the deformation of the insert, crack growth in the laminate and debonding between metal insert and carbon fiber reinforced plastics is necessary. This paper aims for an investigation of the in situ failure behavior during tensile loading of composite sheets equipped with two different types of inserts by means of acoustic emission and computed tomography analysis. An inductive strain gauge was additionally installed underneath the laminate when performing the tensile tests monitored by acoustic emission analysis.