High‐Performance,Monolithic Polyaniline Electrochemical Actuators

New polyaniline (PANI) asymmetric membranes were fabricated using a phase‐inversion technique with hexane as the coagulation bath. These membranes exhibit a dense structure with macrovoids distributed asymmetrically throughout the cross‐section. A stress–strain study demonstrated that the Young's modulus (1.421 GPa) and strain at break (7.6 %) of the new PANI asymmetric membranes prepared from hexane are approximately 12 and 4 times higher, respectively, than the values reported previously for the PANI integrally skinned asymmetric membranes (ISAMs) (123 MPa Young's modulus and 1.8 % strain at break). Furthermore, monolithic electrochemical actuators based on a single PANI asymmetric membrane were constructed, and a bending movement of up to 20 Hz was experimentally recorded in a hydrochloric acid aqueous solution. A lifetime of over 329 500 cycles was determined for these actuators at a ± 2° angular displacement (5 Hz). The lifetime is limited by a bending fatigue that creates a transversal crack on the PANI membrane at the air–water interface. Control over the actuator movement is also manifested by the linear dependences of the bending angle on the charge and of the angular velocity on the current. These relationships are independent of both the kind of applied electric signal and the frequency used.     

Simulation of Facial Muscle Actions Based on Rational Free Form Deformations

This paper describes interactive facilities for simulating abstract muscle actions using Rational Free Form Deformations (RFFD). The particular muscle action is simulated as the displacement of the control points of the control-unit for an RFFD defined on a region of interest. One or several simulated muscle actions constitute a Minimum Perceptible Action (MPA), which is defined as the atomic action unit, similar to Action Unit (AU) of the Facial Action Coding System (FACS), to build an expression.     

Direct manipulation of FFD: efficient explicit solutions and decomposible multiple point constraints

Published online: 25 July 2001     

Influence of the transverse magnetic field intensity upon the electric resistance of the magnetorheological elastomer containing graphite microparticles

The magnetoresistor achieved and presented in this paper is based on magnetorheological elastomer (MRE) with graphite microparticles. It is shown that the resistance R of the magnetoresistor decreases with an increase of the strength H of the transverse magnetic field and of the compression force F, respectively The sum θ of the principal deformations as well as the compresibility module K is determined and the results obtained are discussed.     

路堑边坡施工过程中后缘变形演化分析

在路堑边坡施工过程中,研究边坡后缘的变形趋势可以较早地提供整个边坡的变形的信息,对整个施工过程有实际的工程意义。基于数值模拟和现场监测结果,以漳州招银疏港高速公路A3标边坡(ZK14+165)为例来探索在施工过程中路堑边坡上缘的变形演化过程。结果表明:1)除了新开挖平台由于卸荷引起的变形以外,边坡上缘是产生变形的主要区域;2)随着开挖施工的进行,上缘变形越来越大,靠近开挖面处最大;3)变形发生在坡顶以上10m左右的范围内(针对此开挖高度为38.8m的路堑边坡),变形区域由上缘坡面到开挖面近似螺旋曲线的形状。     

MIG Brazing of Galvanized Thin Sheet Joints for Automotive Industry

MIG welding of zinc-coated thin plates in the automotive industry leads to major issues, mainly zinc evaporation followed by a decrease of corrosion resistance, as well as residual strains and stresses difficult to minimize. The use of a lower heat input technique for joining galvanized steels would bring significant benefit, if the final overall mechanical properties of the joints are adequate for the application. The use of MIG brazing (MIGB) with the recently commercialized alloyed copper-based filler metal is an alternative worth considering. The present paper addresses the MIGB processes, describing the influence of the different shielding gases and the process parameters on the mechanical, corrosion, and metallurgical properties of the joint, when lower heat input procedures are targeted. The paper describes the influence of the gases on the mechanical properties of the brazed joint, both in normal conditions after joining and after corrosion in a salt water environment. Microstructural features of the different zones are discussed. Results of corrosion and tensile tests are presented and interpreted.     

A Unified Approach for Physical and Geometric Modeling for Graphics and Animation

We present a unified approach for geometric and physical modeling using implicit functions, for application to graphics and animation. This method extends previously proposed techniques, and allows the standard finite element method to be directly combined with geometric modeling, resulting in quick calculation of an object's mass and stiffness matrices, and its vibration modes and frequencies. Because the approach is based on an implicitfunction representation, it allows very fast collision detection and characterization. Examples of complex physical and geometric modeling are presented.     

THERMOMECHANICAL APPROACH TO SHRINKING AND CRACKING PHENOMENA IN DRYING

The thermomechanics of partly saturated porous materials is presented as a basis for the construction of mechanistic theory of drying. Based on the balance of mass, momentum, energy, entropy, and the thermodynamics of irreversible processes the constitutive laws for heat and mass transfer and the physical relations between stresses, strains, moisture content and the temperature are developed. Using the London-Heitler's formulas for cohesion and the Condon-Morse curve performing the bond energy of two atoms versus their distance, a theoretical strength of material during drying process is estimated. By analogy to Griffith's concept, a fracture criterion is formulated. Finally, the acoustic emission as a possible method for detection of fracture process in dried materials is discussed.     

Prediction of Permanent Deformations in Pavements Using a High-Cycle Accumulation Model

The present paper discusses the application of a high-cycle accumulation (HCA) model originally developed for sand for the prediction of permanent deformations in an unbound granular material (UGM) used for base and subbase layers in pavements. Cyclic triaxial tests on precompacted samples of an UGM have been performed in order to validate and calibrate the model. The stress amplitude, the initial density, and the average stress were varied. The test results are compared to those of air-pluviated samples of sand (subgrade material). Some significant differences in the behavior of both materials under cyclic loading are outlined. It is demonstrated that the functions describing the intensity of accumulation can be maintained for an UGM with different material constants, but that the flow rule must be generalized in order to describe the anisotropy. Recalculations of the laboratory tests show a good prediction of the modified HCA model.