Damage Constitutive Relationship of Coupled Plasticity-creep for Magnesium Alloy

Based on a simple mechanical model and an appropriate definition of generalized time,a constitutive equation is obtained for coupled plasticity and creep behavior of materials.A damage evolution based on a spherical void model for mixed hardening materials is obtained by means of Gurson's model.The damage evolution law is embedded in the adopted constitutive equation,and a damage constitutive equation is obtained for coupled plasticity and creep behavior of die-casting magnesium alloy.The response of magnesium alloy subjected to cyclic loads is analyzed.The validity of the proposed model is demonstrated by the satisfactory agreement between the experimental and calculated results.     

Experimental studies on the energy absorption property of aluminum foam filled steel pipe under transverse compression

To understand the energy absorption property of aluminum foam-filled steel pipes and the energy absorption property affected by aluminum foam filler, the energy absorption ability and transverse compression property of steel pipes and aluminum foam-filled steel pipes are tested. The results show that the normal stress-strain curve of steel pipes is similar with that of cellular materials. The normal yield stress of a steel pipe with a large diameter under transverse compression is lower than that with the same wall thickness but a small diameter. The deformation mode of steel pipes can be changed by the filling of aluminum foam. The aluminum foam filler improve the energy absorption ability of steel pipes. The effect of aluminum foam density on the energy absorption ability of steel pipe is small, and the effect of pipe diameter on the energy absorption ability of aluminum foam-filled steel pipes is large.     

Application of ultrasonic detection for partial discharge to cable terminals

The mechanical properties, phase change energy storage, environmental protection, and recycling of building materials are extensively studied, but few studies focus on the mercury adsorption of different building materials. Five types of cement brick powder including foam concrete, red brick, aggregate and gravel as well as several standard concrete blocks were exposed to gaseous mercury in constant temperature to determine most vulnerable building material to mercury contamination and the contamination depth of concrete blocks.Results showed that small particle contributed to large mercury adsorption, however different performance was found amongvarious materials. Red brick was the likely to have strong adsorption capacity followed by foam concrete and gravel. For concrete block,the pollution mainly concentratedat the 0~1.5cm of the surface. As a result, for some seriously mercury polluted factories and workshops, mercury pollution can be removed by peeling the skin of the buildings before demolition, renovation process.     

Equivalent Constitutive Equatlons with Polariiy and the Mechanism of Storing Energy of Honevcomb Materials in Plane Deformation

Equivalent couple-stresses and asymmetric equivalent stresees are introduced todescribe the equivalent constitutive equations of honeycomb materials in plane deformation,It is in-dicated from the field analysis of plane deformation accordin8 to the obtained constitutive equations-that this type of materials is of excellent capacity of storing energy.     

A CONSTITUTIVE LAW FOR CYCLIC BEHAVIOR OF A CLASS OF TWO-PHASE STEELS

Based on a thermomechanically consistent mechanical model, the constitutive law for a class of complex two-phase materials with locking-in inter-phase residual stress capability is proposed. The developed model contains the current plastic strain in its hereditary integral so that the main features of the above materials subjected to cyclic loading can be well described. The developed model can include both the endochronic constitutive equation and Bower' s empirical formula as special cases. The cyclic plasticity and ratcheting of OFHC copper (single-phase material) and rail steel BS1l(two-phase material)are analyzed and compared with experimental results     

Equivalent Coustitutive Equation of Honeycomb Materials with Equivalent Couple Stresses within Plane Deformation

Equivalent couple stresses and non-symmetric equivalent stresses are introducedto describe the equivalent constitutive equation of honeycomb materials within plane deformation.Itis necessary for the materials of macroscopic polarity induced by some mesostructures.     

结构消(耗)能元件芯材SN490B本构关系数值模拟

采用消(耗)能元件的结构在遭受地震作用时,元件芯材首先屈服进入塑性阶段,利用其滞回变形消耗地震输入能量,保护主体结构,元件芯材本构关系的数值模拟是对采用消(耗)能元件结构进行抗震分析与设计的基础。为更真实地模拟结构消(耗)能元件芯材在单调和循环荷载下的本构响应,更准确地对采用消(耗)能元件结构进行结构弹塑性地震响应分析,对常用作消(耗)能元件芯材的日本高延性钢材SN490B的单调、循环加载本构及循环骨架曲线进行了数值模拟,包括：采用Esmaeily-Xiao二次流塑性模型模拟材料在单调荷载作用下弹性段、屈服段、强化段和二次流塑段4个阶段;采用混合强化模型模拟材料循环荷载作用下的本构响应,运用大型通用有限元软件ABAQUS结合数值模拟参数对16种不同循环加载制度下的循环加载试验进行模拟,并与试验结果进行对比;采用Ramberg-Osgood模型、无量纲化的Ramberg-Osgood模型及两段式模型模拟循环骨架曲线。研究结果表明：所采用数学模型可以较好地模拟SN490B钢材单调、循环加载本构响应及循环骨架曲线,数值模拟与试验结果拟合较好。     

Dissipative Energy Based Description for Hardening and Its Application to Non-proportional Cyclic Plasticity

The heterogeneous nature of metallic materials result in residual microstress fields during plastic deformation.The energy stored in the residual microstress fields affects the subsequent plastic deformation. Based on this concept, a nonclassical constitutive model is developed. On the other hand, it is found that there exists difference of dissipative plastic energy between different plastic strain paths. A dissipative plastic energy based hardening parameter is proposed and introduced into the hardening function, which isthen embedded in the non-classical constitutive model. The stress responses of 304 stainless steel subjected to biaxial non-proportional loading are analyzed and the results coincide well with the experimental results.     

Effective Electromechanical Coupling Property of Multiphase Dielectrics

A new way of defining the effective physical quantities by other apparent physical quantities is proposed. Accordingly, a new framework is induced to construct the effective electromechanical coupling constitutive equation of multiphase dielectric materials .In this framework, a special mode is studied. The effective constitutive equation of transversely isotropic multi-layer multiphase dielectrics is set up, and the expression of effective electromechanical coupling constitutive equation of transversely isotropic multi-layer multiphase in plane-stress is given.     

Rock Damage Viscoplastic Constitutive Relationship with Compress

A viscoplastic constitutive relationship with compress is proposed for damaged rock materials based on a thermomechanically consistant mechanical model.The proposed relationship takes into account the compress and damage.The validity of the proposed model is verified by comparing theoretical and experimental results of rock subjected to shock loading with compress.     

Development of Water Based Coating for Lost Foam Casting

The coating is one of the most important auxiliary materials of lost foam casting. In order to reduce the cost of coating for lost foam casting, water based coating has been developed. Refractory material of quartz sands that have three kinds of grain size distribution was used. All coatings were made into paste form by sand roller mill. The paste form was stirred into liquid coating by adding some water in stirrer, then measuring their properties. The developed coating has relative concentrated grain size distribution and consists of quartz sand 100%, bentonite 4%, polyvinyl acetate emulsision 2.5%, CMC 0.5% and other accessories. The coasting has low cost and excellent processing properties, which is applicable to produce nodular iron casting.     

建筑垃圾细料生产流动化回填材料的性能

以灰砂比0.03、0.05和0.08,粉砂比0、0.05、0.1、0.15和0.2为设计参数,对建筑垃圾回填材料进行设计。通过试验对回填材料的流动性(流动度、泌水率)、无侧限抗压强度以及应力应变曲线、本构关系模型和弹性模量等进行研究。研究结果表明:回填材料的流动度受水固比影响较大,两者接近线性关系;流动度在200~250 mm范围,泌水率在4%~8%之间;回填材料抗压强度与灰砂比和水固比之间存在很好的幂指数关系;回填材料应力应变曲线形状与普通混凝土的相似,在此基础上提出回填材料的本构关系模型;回填材料无侧限抗压强度与弹性模量之间存在很好的指数关系。     

Nonlinear Response and the Dynamic Stability of Viscoelastic Cable

Based on one dimensional constitutive equations of Revlon materials and the motion equations of the cable, the partial differential equations of the viscoelastic cable in inner and outer of plan under the gravity are investigated. Using Galerkin's method, a system of nonlinear ordinary equations is obtained. The analysis methods of the dynamic stability of viscoelastic cable are given. Finally, the effect of dynamic response of the cable, which is produced by elastic and viscoelastic parameters, is testified by the research of digital simulation.     

Foaming accelerators for polypropylene microcellular foamed plastics

The effects of three foaming accelerators, ZnO, nanometer ZnO, and ZnO/Zn(st)2, on the thermal decomposition property of foaming agents and the ability to create microcellular foam in polypropylene (PP) microcellular foaming plastics are studied. The influence of these accelerators on the microcellular structure of PP microcellular foaming plastics is analyzed by using a thermogravimetry technique. The dispersion of foaming accelerators in resins is observed using scanning electron microscopy. It is shown that the compositing foaming accelerators exhibite a comparatively better dispersion. The properties of different accelerators containing foaming materials are investigated and compared. Compared to those without foaming accelerators, the impact strength of PP microcellular foaming plastics with foaming accelerators is significantly enhanced.     

浅述啤酒泡沫的研究现状

啤酒泡沫被誉为"啤酒之花",已作为啤酒质量的一项重要感官指标列入国家标准GB 4927—91,啤酒泡沫稳定性是保证啤酒质量的关键。根据目前关于啤酒泡沫的研究,系统地阐述啤酒泡沫的有利因素和不利因素,在啤酒生产过程中如何采取有效的控制措施以及添加啤酒泡沫稳定剂,为啤酒生产企业解决啤酒泡沫稳定性的问题提供参考。     

Quantitative analysis of flow and heat transfer in graphite foam

Graphite foam is a new type of material which possesses good thermal properties such as low density, high thermal conductivity, and high specific surface area. Based on the micro-structure of graphite foam, models are designed to analyze flow an