清洁压裂液的研究与应用

粘弹性表面活性剂(VES)压裂液(又称清洁压裂液)的使用改变了传统聚合物压裂液生产操作方式,可以减少传统压裂液对地层的损害和污染.分析归纳了目前国内外清洁压裂液体系的组成、作用机理及研究应用情况.对我国开展清洁压裂液的研究提出了一些建议.     

考虑孔隙损伤的黏弹性材料压力容器问题

应用线弹性微结构理论和黏弹性理论,讨论了带孔隙损伤的黏弹性材料压力容器问题。所得的解是准静态的。应力的解和线弹性的压力容器的应力解相同,位移场和损伤场与带孔隙损伤的线弹性材料压力容器问题的位移场和损伤场相似。     

粘弹性板热机耦合非线性振动（Ⅰ）——动力学模型

建立了横向周期荷载、面内均布荷载和温度场作用下,考虑热传导效应的粘弹性矩形板的热机耦合非线性动力学模型.基于薄板大挠度Karman理论和用Boltzmann叠加原理描述的粘弹性材料本构方程、动力学平衡方程和热粘弹能量原理建立了考虑热传导效应的粘弹性矩形板的热机耦合非线性动力学模型,并用Galerkin方法将该热机耦合非线性动力学模型转化为非线性微分-积分动力系统.研究表明:1)在热传导系数和热膨胀都为0时,该热机耦合非线性动力学模型退化为粘弹性板动力学模型;2)在热传导系数为0而热膨胀不为0时,该热机耦合动力学模型简化为仅考虑热膨胀时的粘弹性板动力学模型;3) 当材料的粘性项为0时,即动力学模型中积分项为0时,该热机耦合动力学模型退化为热机耦合弹性板动力学模型.     

三参量模型粘弹性圆柱体运动微分方程的建立

从粘弹性圆柱体的微单元出发,通过分析微单元的受力情况,运用D’Alembert原理,建立轴向流动中粘弹性圆柱体的运动微分方程。然后引入三参量模型的微分算子,得到了轴向流动中三参量模型粘弹性圆柱体的运动微分方程,最后再分别引入无量纲量,将三参量模型的微分方程化为无量纲方程。     

New approach for calculating permanent deformation in asphalt pavement

A new approach using the Fiber Bragg Grating(FBG)sensor and viscoelastic model to monitor and analyze the internal strain and temperature of asphalt pavement is proposed.Some parameters including peak strain,temperature and loading time were calculated with the application of multi-dimensional sensors group.These parameters were incorporated with viscoelastic model of five units to evaluate the permanent deformation of pavement.An application example was conducted,and the results show that it is feasible to analyze and calculate the permanent deformation of pavement structures with FBG sensors.     

三参量模型粘弹性圆柱体轴向流动中的动力特性

对悬臂粘弹性圆柱体轴向流动中的动力特性进行了研究,计算模型采用三参量模型,对特征方程进行了推导,给出了在质量比β(β=0.5)一定,改变无量纲延滞时间α和无量纲弹性系数比λ的情况下,悬臂三参量模型粘弹性圆柱体的前三阶模态无量纲复频率ω的实部及虚部与无量纲流速v之间的关系曲线图.研究结果表明:在无量纲弹性系数比λ和质量比β一定时,随着无量纲延滞时间α的增加,及在无量纲延滞时间α和质量比β一定时,随着无量纲弹性系数比λ的增加,第一阶模态发生单一模态颤振及再次稳定的无量纲临界流动速度都在减小.     

考虑桩-土相互作用的粘弹性土中管桩的纵向动力阻抗分析

在考虑三维波动的条件下,利用分离变量法求解了管桩桩周和桩芯粘弹性土层的竖向振动,对粘弹性土层中弹性端承摩擦管桩与土层的耦合振动问题进行了研究,得到了粘弹性土层中管桩的复刚度和桩顶导纳.讨论了桩周土和桩芯土剪切模量比、粘滞阻尼系数比和管桩内外半径比对管桩竖向动力阻抗的影响.     

加速黏弹性传动带的分岔和混沌动力学特性

为了探索黏弹性传动带的分岔和混沌动力学特性,基于几何非线性,利用Hamilton原理建立了黏弹性传动带的非平面横向非线性动力学方程.对黏弹性传动带的偏微分动力学方程进行Galerkin截断,得到了常微分方程.利用四阶Runge-Kutta法对得到的常微分方程组进行数值模拟.模拟结果表明,黏弹性传动带系统存在分岔和混沌现象.     

Dynamic viscoelasticity of low‐density polyethylene/in‐situ‐grafted carbon black composite

The study on the dynamic viscoelastic properties of grafted carbon black (g‐CB) filled low‐density polyethylene (LDPE) was carried out. Because of formation of CB networking, the characteristic modulus plateau and loss tangent arc appears. Addition of grafting monomer like butyl acrylate (BA) and acroleic acid (AA) enhances the interaction between particles and matrix due to accelerated formation of micronetworking in the composites induced by forming branch chains of AA and BA with multiunit. The decrease of the temperature corresponding to α_c mechanical relaxation together with AA (BA) addition given by the position of loss tangent (tan δ) peak for LDPE is owed to the formation of long‐chain polymer grafted between CB and the matrix, which facilitates the slip of the lamella of LDPE. The influence of maleic anhydride (MA) on enhancing interaction between LDPE and CB is not so pronounced, as compared with AA and BA because of no formation of long chain between CB particle and polymer matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4127–4132, 2006     

Thermally stimulated creep (TSCr) study of viscoelastic behavior and physical aging of a polymeric matrix composite for spacecraft structures

Thermally Stimulated Creep (TSCr) mechanical spectroscopy has been used to analyze molecular movements in KMU‐4lcarbon/epoxy composite material around the glass transition temperature. This technique is powerful to characterize the microstructure and micromechanical properties of the epoxy matrix and their evolution upon thermal aging. Three cooperative submodes have been distinguished by resolving the fine structure of the material complex α‐retardation mode. The elementary processes constituting this mode possess activation enthalpies and preexponential factors that strongly depend on the thermal history of the sample. The activation parameters of the composite are subject to perceptible evolution due to postcuring degradation. The α‐mode associated complex spectrum shifts towards higher temperatures by 27°C as a consequence of a series of quenching in the temperature range 260 to 0°C; the material shows a rise in the fragility and a deterioration in the crack‐growth resistance qualities. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 342–350, 2002