The motion of a sphere with weak nutation on a rough horizontal plane

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送纸机构纸张控制方程及卡纸现象数值分析

卡纸现象是打印机和复印机送纸机构常见故障之一,广泛存在于各种介质的传送系统中．为解决该问题,需要研究纸张在送纸机构中的运行规律和受力特点．根据送纸机构的原理,建立纸张在辊轮间运动的计算模型,并推导这一过程中的纸张运动方程．理论推导表明机构的材料与尺寸对卡纸有影响;同时,利用多体动力学分析软件RecurDyn,建立送纸机构仿真分析模型,研究送纸机构运行状态并分析在纸张脱离辊轮后各个因素对卡纸现象的影响,获得纸张与导板间不同的摩擦系数、主动辊轮转速、纸张模量及厚度变化对机构运动影响的规律;最后对比了实验与仿真的扭矩结果,来验证仿真方法的可靠性．结果表明,在纸张被辊轮夹持阶段,纸张运动主要受机构材料和尺寸影响;在纸张脱离辊轮后,纸张运动主要受摩擦力和接触力的影响,并发现随着纸张与导板间摩擦系数的增加、辊轮转速的减小、纸张模量及厚度的变大,机构中容易发生卡纸现象．研究结果可为解决卡纸故障提供指导．     

Nonlinear imbibition influence on the hygro-mechanical bending response of paper due to its interaction with water

The bending response analysis of a piece paper as a result of its interaction with water is studied to provide a better understanding of the problem that is dominated by water imbibition into paper. Three phenomenon that take simultaneously place are considered in this model: (i) water imbibition (ii) swelling of fibers and (iii) the softening effect on paper due to the water penetration. The water penetration into paper is modeled including the nonlinear imbibition phenomenon into paper. Numerical solution of the problem is carried out using MatLab^®. The influence of the nonlinear imbibition on the bending response is studied. The proposed model is more accurate and provides a better understanding of the problem compared to previous models presented in earlier works. Moreover, the formulation requires only four parameters to characterize the hygro-mechanical bending response of paper. Finally, the results show a good agreement with the experimental measurements reported in the literature.     

Elasto-plastic approach for paper cockling phenomenon: On the importance of moisture gradient

Cockling of paper is a common problem occurring in the production, storage and end-use of paper. It is usually induced by a moisture content change. In many cases, cockling is an irreversible phenomenon; i.e. the initial shape is not obtained although the initial moisture content is restored. This kind of moisture content change occurs in copying machines and in the printing process, for example. In this paper, we present a continuum mechanical model, which is used to study the irreversible cockling of paper. In the model, paper is treated as an orthotropic elasto-plastic material and the model takes into account the small-scale variation of fibre orientation. The model is used to show the importance of the through-thickness moisture gradient on the cockling phenomenon during a cyclic moisture content change. The results suggest that the moisture gradient is a crucial factor for the irreversible cockling.     

The influence of paper compressibility on ink penetration

Summary An analysis on the compressible nature of paper shows that under high pressures the pore size is linearly related to the square root of pressure. An expression for the penetration of ink into paper as a function of pressure is derived and agrees satisfactorily with experimental results. It is also shown that the mean hydraulic radius of the pores of a paper can be calculated directly from the fall in the diffuse reflectance of paper caused by the penetration of black ink under pressure.     

纸质构件力学性能试验研究

对铅化纸制作的纸杆和纸带进行了力学试验, 分析了其力学性能, 结果表明:纸杆应力应变曲线存在线弹性段, 弹性模量主要集中在200$\sim$400\,MPa, 并具有一定的离散性. 而纸带抗拉曲线呈明显的非线性特征, 极限拉应变主要集中在0.015$\sim 对铅化纸制作的纸杆和纸带进行了力学试验, 分析了其力学性能, 结果表明:纸杆应力应变曲线存在线弹性段, 弹性模量主要集中在200$\sim$400\,MPa, 并具有一定的离散性. 而纸带抗拉曲线呈明显的非线性特征, 极限拉应变主要集中在0.015$\sim 对铅化纸制作的纸杆和纸带进行了力学试验, 分析了其力学性能, 结果表明:纸杆应力应变曲线存在线弹性段, 弹性模量主要集中在200$\sim$400\,MPa, 并具有一定的离散性. 而纸带抗拉曲线呈明显的非线性特征, 极限拉应变主要集中在0.015$\sim 对铅化纸制作的纸杆和纸带进行了力学试验, 分析了其力学性能, 结果表明:纸杆应力应变曲线存在线弹性段, 弹性模量主要集中在200$\sim$400\,MPa, 并具有一定的离散性. 而纸带抗拉曲线呈明显的非线性特征, 极限拉应变主要集中在0.015$\sim对铅化纸制作的纸杆和纸带进行了力学试验,分析了其力学性能,结果表明:纸杆应力应变曲线存在线弹性段,弹性模量主要集中在200～400 MPa,并具有一定的离散性.而纸带抗拉曲线呈明显的非线性特征,极限拉应变主要集中在0.015～0.025之间,纸带的粘结状态对试件的极限拉应变有较大的影响.     

无拉力Winkler地基梁静力分析的线性互补法

提出了无拉力Ｗｉｎｋｌｅｒ地基梁弯曲的线性互补法．将地基反力作为未知量而获得了一组地基与梁之间相对竖向位移和反力的线性互补方程．计算结果表明本文解与文［２，３］解吻合良好。     

一类弱非线性振动问题的插值摄动解法

用插值摄动法［１］求解一类有阻尼的弱非线性振动问题。算例表明，当小参数很小时，本文结果和多尺度法的一级近似结果十分接近。当小参数不是很小时（即接近于强非线性振动时），本文结果，仍然相当准确，并优于多尺度法的一级近似结果。     

On dissipative effects of paper web adhesion strength

This work is concerned with the adhesion strength between a paper web and a metal roll surface, which is a common situation in paper machines world-wide. It is shown that the classic expression relating the work of adhesion to the peeling angle and web tension is, in general, insufficient. An improved model is suggested to take into account the energy dissipation due to elastic–plastic deformation behavior of wet paper materials. To judge the model, an industrially relevant example of wet newsprint and a mild steel surface is studied. It is found that the agreement between theory and experimental observations is excellent. A key result is that elastic–plastic material behavior must always be included for wet paper materials in peeling processes.     

Existence and continuous dependence results in the theory of interacting continua

This paper is concerned with the linear theory for binary mixtures of elastic bodies. In the first part of the paper we study boundary-value problems of the equilibrium theory. Existence and uniqueness theorems are established. The second part of the paper is devoted to the dynamic theory. We use the semigroups theory of linear operators to obtain existence and continuous dependence results.