沥青路面层状粘弹性半空间轴对称问题的求解

沥青路面中的沥青材料是一种典型的粘弹性材料，利用积分变换和传递矩阵的方法推导了沥青路面多层粘弹性半空间轴对称问题的解析解，引入了F.Durbin的方法实现Laplace逆变换，通过实例计算路表弯沉表明初始时段所得结果与弹性解基本一致，随着时间的推移，沥青路面多层粘弹体系路表弯沉增大，说明随时间的推移，沥青材料的粘性起到更大的作用，反映了粘弹材料的蠕变变化规律，这与沥青路面实际情况相符。此方法可以很容易扩大到沥青路面多层粘弹体系动力学问题之中。     

On predicting abrupt contraction flows with differential and algebraic viscoelastic models

The numerical simulation of flows through a planar contraction at low Reynolds number is considered for Newtonian and for viscoelastic fluids. The recently proposed algebraic extra-stress model (AESM) derived from the differential constitutive equation for an Oldroyd-B fluid is extended to a Phan-Thien–Tanner fluid. The approach is based on the exact polynomial representation using a three-term tensor basis. It is also shown that the algebraic formulation reproduces exactly the extra-stress tensor components for pure shear and for pure elongation flow. A parameter based on the strain rate and the rotation rate tensors is presented to identify the regions of the flow where the AESM model produces exact results. A second-order numerical scheme accurate in time and space, based on the finite volume method using a staggered grid has been applied to solve the conservation and constitutive equations for the Newtonian and viscoelastic flows. The numerical simulations for the viscoelastic fluids have been done using the classical constitutive equations in a differential form and the algebraic extra-stress model. Excellent agreement between the extra-stress values is obtained with the two different approaches, showing the viability of AESM.     

承载边简支另二边各种支承的对称层合板的线性粘弹屈曲分析

本文在线性粘弹理论的基础上,研究了承载边简支另二边为各种支承的对称层合板的粘弹屈曲问题。线性粘弹蠕变柔量可用宏观力学实验获得,用有限条方法解虚功方程,方法简明实用,算例讨论了层合板铺层情况,板的几何尺寸以及不同支承情况对层合板粘弹效应的影响,得到了一些有意义的结论。     

Maxwell模型粘弹性矩形厚板固有横向振动

由于各向同性粘弹性体剪应力-角应变的本构关系与应力-应变的本构关系相似,据此可得到Maxwell模型粘弹性矩形厚板固有横振微分方程。并讨论了Maxwell粘弹性矩形厚板的振动特性。     

Ternary Gels of a Polymer Blend and a Recycled Oil: Their Use as Bitumen Modifiers

A blend of random ethylene‐vinyl acetate copolymer (EVA) and triblock styrene‐butadiene‐styrene copolymer (SBS) was dissolved in a recycled engine oil to obtain ternary thermoreversible gels. As the temperature was increased, first a network associated with EVA disappeared, and a second one associated with SBS dominated, maintaining the elastic response of the system. The principal advantage of these ternary systems is that their mechanical properties and thermal stability are better than that of binary gels. These gels, made from waste, can be used as bitumen modifiers to obtain binders of improved properties and good stability, which are useful for road surfacing.

Temperature sweeps of elastic modulus performed at a frequency of 1 Hz.     

高层建筑顶部幕墙结构的风振控制研究

考虑主体结构与顶部幕墙结构的相互作用,采用主体结构层模型-顶部幕墙结构杆系模型分析结构的风效应和顶部幕墙的风振鞭梢效应,应用增设内置式粘弹性阻尼器支撑的控制方法来减小顶部幕墙的风振响应.通过对一栋42层的高层建筑的计算分析表明:采用内置式粘弹性阻尼器支撑后,大大地降低顶部幕墙结构的风振位移,为防止顶部玻璃幕墙的掉落增加可靠性.     

确定Kelvin模型粘弹性材料参数的一种实验方法

从Kelvin模型和Euler-bernoulli梁理论出发，利用弹性-粘弹性相应原理和弹性材料动力学理泠得出粘弹性梁的动力学方程。利用中心差分法分析了粘弹性材料悬臂梁的动态函数。根据振动特性，将材料参数与梁应变响应周期及振幅衰减相联系；利用这种联系，提出了测定Kelvin模型粘弹性材料参数的一种简单实验方法；分别取不同长度的橡胶悬臂梁进行了相应的实验，测出了材料的剪切模量和粘性系数；分析实验结果，得出一些有益的结论。     

基于Herrmann变分原理的三维粘弹性增量有限元法及其应用

发展了一种不可压和近似不可压粘弹性增量有限元法,并对固体火箭发动机药柱进行了三维分析。首先从Herrmann泛函出发并结合对应原理导出了适用于不可压和近似不可压粘弹性材料的本构关系,然后根据虚功原理建立了三维粘弹性增量有限元列式,最后对弹性约束的圆柱形中孔药柱进行了不可压和近似不可压分析。结果表明该方法可用于泊松比接近甚至等于0.5的粘弹性问题计算,尤其适用于固体推进剂药柱的结构分析。     

Short-term creep and strength of fibrous polypropylene structures

The short-term creep and strength of fibrous polypropylene structures are investigated. On the basis of these characteristics, we develop the models of linear and nonlinear viscoelastic deformation of materials, specify the fields of their applicability, and study criteria used for the evaluation of the static strength and durability of these composites. __________ Translated from Problemy Prochnosti, No. 6, pp. 77–90, November–December, 2007.     

横向撞击对竖直桩影响的动力分析

针对桩基础施工中使用机械清理桩头时经常遇到的撞击问题,把桩周土当作Winkler地基,运用弹塑性碰撞理论,由拉氏正变换和逆变换解析得到了桩顶受到横向冲击荷载时桩的瞬态横向动力响应;通过变换不同的桩土参数,对有限长桩和无限长桩的最大无量纲响应沿深度的变化曲线进行了分析比较.结合相应的工程实例,对竖直桩的配筋及所能承受的横向撞击速度的临界值(0.22 m/s)作了探讨,并提出了相应的施工改进措施,如控制撞击速度或调整桩身配筋等.