融化巧克力浆料流注特性的实验研究

对融化巧克力浆料进行了实验研究，揭示了其假塑性和触变性，并根据实验结果得到了融化巧克力浆料的全流变本构方程。     

融化巧克力浆料的流变特性

使用NXS－11型旋转粘度计测量融化巧克力浆料流变特性,发现它具有假塑性和触变性．     

压力对冰水固流转化速率影响的实验研究

本文对圆柱形冰块融化过程进行了数学分析,得到了冰水固流转化的数学关系及冰的温度与压力的关系,通过冰块融化实验,研究了压力对融冰速率的影响,通过Matlab曲线拟合与数据分析,得出了圆柱形冰块融化速率与时间随压力变化的经验公式,最后用Ansys进行了数值仿真验证.     

温度增量对冰水固流转化速率影响的实验研究

通过RPH-80型可程序恒温恒湿试验箱研究了温度增量对圆柱体冰块融化速率的影响。研究结果表明:试验箱的温度在0℃~50℃区间内,随着温度增量的增大,圆柱体冰块的融化速率逐渐加快。通过数据分析,得出了圆柱体冰块的温度增量与融化时间、融化速率都呈多项式函数规律变化。选取温度增量为20℃的冰块融化过程进行ANSYS数值仿真验证,得出:圆柱体冰块棱边部分最先开始融化;随着时间的增长,冰块的侧面比上表面开始融化的时间早,这亦与实际的融化状况相符。     

酸碱度对冰块融化速率影响的实验研究

冬季积雪、深部软岩巷道流变、高原冻土翻浆等现象给我们的日常生活和工程建设带来了极大的不便,这些现象都涉及到固体与流体之间的转化现象,因此材料固流转化理论研究具有重要的理论意义和应用价值.本文以酸碱度为自变量,通过冰块融化实验,研究了其对融冰速率的影响,结果显示,随着pH值的增加,冰的融化速率有先变慢后加快的趋势.通过数据分析,得出了酸碱度与融冰速率关系的经验公式,并用Fluent进行了数值仿真验证.     

双螺旋辊式新型磨浆机螺旋套磨损机理的研究

利用金相组织分析和电子显微分析技术,结合生产实际,对已磨损的输料段和磨浆段的螺旋套进行磨损表面形貌分析,探讨螺旋套磨损机理.结果表明:输料段正螺旋套能够将纸浆料旋转送入机壳内,不承受较大的挤压应力,但由于纸浆料中含有腐蚀介质,其主要的磨损失效形式以腐蚀磨损为主,磨料磨损为辅;磨浆段反螺旋套本身无正输送能力,浆料在正输送组件作用下形成高压区,纤维与浆料之间产生较大摩擦力,导致纤维分离,进而使之分丝帚化和压溃,浆料水分降低,其主要的磨损失效形式为高应力磨料磨损,并伴有腐蚀磨损.     

聚丙烯纤维加固土融沉特性的离散元数值模拟研究

针对掺入纤维对土体冻融特性的影响进行离散元数值模拟,首先自研了过程感知融化固结系统,基于融沉试验,提出了微观参数折减法模拟融化过程,分析了纤维掺量、纤维长度、土样高度的影响规律。结果表明：离散元方法可对融沉过程进行较为有效的模拟,并可得到最优纤维掺量,对于模拟工况,最优纤维掺量为0.1%;从融化压缩模量看,纤维长度与掺量为敏感影响因素,土样高度为次要因素;掺入纤维对土体强度与融沉特性的提升效果具有一致性。     

WC／Co硬质合金的磨料磨损性能研究

采用微尺度浆料磨料磨损试验机和钢轮湿磨料磨损试验机,对比考察了不同晶粒尺寸和硬度的ＷＣ／Ｃｏ硬质合金在钢轮湿磨料磨损试验和微尺度浆料磨料磨损试验条件下的磨料磨损性能;同时采用扫描电子显微镜观察分析合金磨损表面形貌,以探讨其磨损机理。结果表明：随着硬质合金试样硬度的增加,其在钢轮湿磨料磨损试验条件下的抗磨能力明显增强;而在微尺度浆料磨料磨损试验条件下,即ＷＣ晶粒粒度与磨料相对尺寸相近时,合金的磨损体积损失与其硬度之间无明显相关性,此时ＷＣ晶粒尺寸是影响硬质合金磨料磨损性能的主要因素,ＷＣ／Ｃｏ硬质合金的主要磨损机理为ＷＣ晶粒的断裂和剥落。     

动脉壁静态力学性质的实验

生命体材料的力学性质具有其特殊性和复杂性．因而,对其进行力学实验研究也具有从实验设计、实验方法到实验技术的特殊性和复杂性．本文详尽地研究了动脉壁三维静态力学实验的方法和技术：进行了四只白兔颈动脉的静态力学性质实验;得到了性态较好的实验结果     

用简化Acierno模型预测LDPE熔体的触变环实验

考察了简化Acierno型本构方程的预测能力．用简化Acierno方程预测了LDPE(Q200)熔体的触变环实验,比较了该方程和变型Huang方程在拟合和预测触变环实验方面的差异．虽然简化Acierno方程只能拟合LDPE熔体的部分触变环实验,但该方程预测的触变环与实验值的偏差较小,而同样的计算条件下,变型Huang方程的预测结果与实验值相差较大．简化Acierno方程的构造比变型Huang方程的构造更为合理．     

Thermistor analog study of dynamic shear in model viscoelastic materials

An electric transmission line analog for studies of the dynamic plane shear of an incompressible viscoelastic material which has a temperature dependent viscosity is described. Thermistors are used to simulate the temperature dependent viscosity. Criteria are established for the similarity of the line and the material. Experiments analogous to constant rate of deformation studies of an elastic material and a material with a single viscoelastic relaxation time are described. More detailed experiments analogous to the deformation of a viscous material at a constant rate of deformation and at constant stress are also described. These show phenomena analogous to necking and fracture.     

An improved Jones-Nelson nonlinear material model and rubber composite lamina analysis

A Jones-Nelson model has been applied to depict nonlinear stress-strain relations of composite laminae, where mechanical properties were expressed by strain energy density. The nonlinear material matrix is only a function of the strain energy density. Then a material model could be conveniently applied under complex stress condition. In this paper, by introducing large displacement stress-strain measurement and varying-Poisson's ratio idea, an improved Jones-Nelson material model is presented, where the expanding problem of material properties and convergence problems are overcome. Meanwhile a discuss of the reorientation of fiber and a material nonlinear analysis of rubber composite lamina under super large deformation conditions are made. The prediction results of improved material model are in fairly good agreement with those of the experiments.     

A thick anisotropic plate element in the framework of an absolute nodal coordinate formulation

In this research, the incorporation of material anisotropy is proposed for the large-deformation analyses of highly flexible dynamical systems. The anisotropic effects are studied in terms of a generalized elastic forces (GEFs) derivation for a continuum-based, thick, and fully parameterized absolute nodal coordinate formulation plate element, of which the membrane and bending deformation effects are coupled. The GEFs are first derived for a fully anisotropic, linearly elastic material, characterized by 21 independent material parameters. Using the same approach, the GEFs are obtained for an orthotropic material, characterized by nine material parameters. Furthermore, the analysis is extended to the case of nonlinear elasticity; the GEFs are introduced for a nonlinear Cauchy-elastic material, characterized by four in-plane orthotropic material parameters. Numerical simulations are performed to validate the theory for statics and dynamics and to observe the anisotropic responses in terms of displacements, stresses, and strains. The presented formulations are suitable for studying the nonlinear dynamical behavior of advanced elastic materials of an arbitrary degree of anisotropy.     

DYNAMIC CHARACTERISTICS IN INCOMPRESSIBLE HYPERELASTIC CYLINDRICAL MEMBRANES

In this paper, the dynamic characteristics are examined for a cylindrical membrane composed of a transversely isotropic incompressible hyperelastic material under an applied uniform radial constant pressure at its inner surface. A second-order nonlinear ordinary differential equation that approximately describes the radial oscillation of the inner surface of the membrane with respect to time is obtained. Some interesting conclusions are proposed for different materials, such as the neo-Hookean material, the Mooney-Rivlin material and the Rivlin-Saunders material. Firstly, the bifurcation conditions depending on the material parameters and the pressure loads are determined. Secondly, the conditions of periodic motion are presented in detail for membranes composed of different materials. Meanwhile, numerical simulations are also provided.     

Mathematical characterization and identification of remodeling,growth, aging and morphogenesis

A clear demarcation between various processes of material evolution is established and the implications of the symmetry type on our ability to distinguish between them are investigated. The general features of the various types of material evolution are emphasized by establishing a spatio-temporal analogy between material uniformity and processes of material evolution.     

Axisymmetric deformations of circular rings made of linear and Neo-Hookean materials under internal and external pressure: A benchmark for finite element codes

The axisymmetric deformations of thick circular rings are investigated. Four materials are explored: linear material, incompressible Neo-Hookean material and Ogden's and Bower's forms of compressible Neo-Hookean material. Radial distributed forces and a displacement-dependent pressure are the external loads. This problem is relatively simple and allows analytical, or semi-analytical, solution; therefore it has been chosen as a benchmark to test commercial finite element software for various material laws at large strains. The solutions obtained with commercial finite element software are almost identical to the present semi-analytical ones, except for the linear material, for which commercial finite element programs give incorrect results.     

Finite element simulation of deformation behaviour of cellular rubber components

This paper presents a new prospect of investigating the mechanical behaviour of cellular rubber using a porous hyperelastic material model within the framework of homogenisation method to consider pore volume fraction. There are number of hyperelastic material models to describe the behaviour of homogeneous elastomer, but very few to characterise the complex properties of cellular rubber. The analysis of dependence of material behaviour on pore density using the new material model is supported with experiments to characterise the actual material behaviour. The finite element simulations are then followed by compression load tests to validate the material model.     

Internal viscosity in polymer kinetic theory: shear flows

The Gaussian closure method and Brownian dynamics simulations have been used to calculate the shear material properties of a dilute solution of Hookean dumbbells with internal viscosity. Results for the zero-shear-rate material properties and small amplitude oscillatory shear material properties have been found analytically, and numerical results for the steady state shear material properties are also presented. Two interpretations of the stress tensor are investigated and results are compared. Brownian dynamics simulations are used to obtain material properties of the Hookean dumbbell with internal viscosity without approximations. These simulation results are compared with the perturbation solution of Booij and van Wiechen as well as with a new Gaussian closure solution. Also presented are the contracted distribution functions as derived from the Gaussian closure method and from Brownian dynamics simulations.     

Neural network optimization of material composition of a functionally graded material plate at arbitrary temperature range and temperature rise

Summary A neural network model is applied to optimization problems of material compositions for a functionally graded material plate with arbitrarily distributed and continuously varied material properties in the thickness direction. Unsteady temperature distribution is evaluated by taking into account the bounds of the number of the layers. Thermal stress components for an infinite functionally graded material plate are formulated under traction-free mechanical conditions. As a numerical example, a plate composed of zirconium oxide and titanium alloy is considered. In the optimization problem of minimizing the thermal stress distribution, the numerical calculations are carried out making use of the neural network. The optimum material composition is determined by taking into account the effect of temperature-dependence of material properties. The results obtained by neural network and ordinary nonlinear programming method are compared. Received 3 March 1998; accepted for publication 22 May 1998