THE UNCERTAIN EIGENVALUES ANALYSIS OF STRUCTURES WITH UNCERTAIN PARAMETERS

This paper presents a method for estimating the upper and lowerbounds of eigenvalues of structures with uncertainties. The uncertainparameters re described by the convex model. A numerical ex- ample ofthe frame structure is given to illustrate the efficiency of themethod.

Microstructure and Wear Resistance of Ductile Cast Iron Laser Clad with Ni-Ti-Co-C

Using electrode as laser cladding materials, the microstructure and wear resistance of laser clad layer of ductile cast iron was studied. The laser clad layer can be subdivided into the melted zone where existed large amounts of austenite, graphite nodules and some carbides, and the solid state transformation zone which included martensite and austenite below the melted zone. The Ti combined with C to form TiC increasing the wear resistance; The Co significantly increased the wear resistance compared with Ti.

Influence of Ti on MC Carbide in M2 Steel

Influence of Ti on MC carbide of M2 high speed steel was investigated by experimental observation, thermodynamic calculation and crystallographic calculation. With addition of Ti into M2 steel, large quantities of dispersed TiC particles formed in the steel melt at higher temperature than that of the formation of MC carbide. TiC can act as heterogeneous nuclei for the crystallization of MC carbide particles, and therefore promote the formation of blocky MC carbide.

Effect of Si, Al and Bi on Structure and Properties of As-welded and Austempered Ductile Iron Weld Metals during Gas Welding

Effect of Si, Al and Bi on the microstructure and mechanical properties of as-welded and austempered ductile iron weld metals has been studied with SEM, TEM, X-ray diffraction, image analysing system, tension and other test methods. Results show that increasing weld Si, Al and Bi content favours improving the chilling tendency of as-welded ductile iron weld and mechanical properties of austempered ductile iron weld and the mechanism is also discussed. On this basis the optimum chemical composition of weld is determined. The mechanical properties of weld and welded joint after austempering can match those of austempered ductile iron.

A FINITE ELEMENT ANALYSIS OF THE LARGE PLASTIC DEFORMATION BEHAVIOR OF AMORPHOUS GLASSY CIRCULAR POLYMERIC BARS

The BPA eight-chain molecular network model is introduced into the finite element formulation of elastic-plastic large deformation. And then, the tensile deformation localization development of the amorphous glassy circular polymeric bars (such as polycarbonates) is numerically simulated. The simulated results are compared with experimental ones, and very good consistence between numerical simulation and experiment is obtained, which shows the efficiency of the finite element analysis. Finally, the influences of the microstructure parameter S-ss on tensile neck-propagation and triaxial stress effect are studied.

ADAPTIVE EIGENFREQUENCY ANALYSIS BY IMPROVED r-AND h-ADAPTIVE FINITE ELEMENT METHOD BASED ON PERTURBATION AND ELEMENT ENERGY RATIO

A new adaptive technique of r-and h-version for vibration problemsutilizing the matrix per- turbation theory and element energy ratiois proposed. In structural vibration analysis, through the r-conver-gence adaptvie finite element process, mesh optimization can berealized. In the light of the judgement on the changes in themagnitude of the element energy ratio, local refinement can beachieved in the process of h- convergence adaptive finite element sothat more accurate finite element solutions can be obtained with asfew meshes as possible. Many numerical examples are given and theproposed approach is shown to be feasible and effective.

NUMERICAL SIMULATION FOR THE SIMPLE SHEAR TEST IN AMORPHOUS GLASSY POLYMERS

In this paper , a driving stress finite element method ofelastic-plastic large deformation based on implicit time integratingalgorithm and an eight-chain molecular network model is used for thenumerical simulation of the simple shear test ofpolycarbonate(PC)materials. The simulated results are compared withexperimental ones. The strain localiztaion propagation for the shearband deforma- tion for simple shear deformation is investigatednumerically. The effects of microstructure parameters in the model onstrain softening and orientation hardening of the PC are discussed indetail.

STATIC REANALYSIS FOR TOPOLOGICAL MODIFICATIONS OF STRUCTURES

A procedure for reanalysis of various structures subjected tovarious topologic modifi- cations is presented. The procedure isbased on the results of a single exact analysis and the factoriza-tion of the stiffness matrix of initial structures. It is suitablefor the addition of joints, where the number of the degrees offreedom is increased. The method deals with the stiffness matrix ofstruc- tures directly, so it can be used with a general finiteelement system. It is shown that the proposed ap- proximation methodis most effective in terms of accuracy, efficiency, and ease ofimplementation.

Effect of Boron on Carbide Morphology of High CrLedeburite Steel

The effect of boron-on carbide morphology of high Cr ledeburite steel has been studied. The results showed that B had obvious influence on eutectic carbide morphology in solidification structure and carbide granulation at high temperature. The addition of 0.02 similar to 0.05 wt pet B changed carbide morphology in solidification structure from strip eutectic and rosette eutectic into divorced eutectic. B accelerated carbide granulation through increasing unstability and lattice distortion of carbide and element diffusion, Granular carbide could be achieved when heated at 1150 degrees C for 1.5 h.

Size-dependent Initial Sintering Temperature of Ultrafine Particles

A model for the size-dependent initial sintering temperature of ultrafine particles was established. The theoretical predictions for the size-dependent sintering temperature of W, Ni and Ag ultrafine particles are consistent with the available experimental evidence. (Edited author abstract) 18 Refs.

Development of a New Welding Material for Arc Welding of As-cast Ferritic Ductile Iron

By using the nickel welding wire, the effect of alloying elements on the chilling tendency of partial fusions zone (PFZ) of arc-welded ferritic ductile iron and the mechanical properties of weld metal have been systematically studied. On this basis, a new nickel electrode for arc welding of ferritic ductile iron (QT400-17) was developed for the first time. The mechanical properties of its weld metal can match those of ferritic ductile iron. The width of carbide layer (WCL) in PFZ is significantly decreased, the welded joint has excellent machinability and the weld metal has high hot cracking resistance. (Edited author abstract) 3 Refs.

Progress of Nonequilibrium Solidification Theory

The theory related to nucleation, interface kinetics, micromorphology evolution and microscopic growth during nonequilibrium alloy solidification was reviewed. Methods for quantitative analysis of nucleation rate, the criterion of marginal stability, nonequilibrium partition coefficient, as well as the relationship between growth rate with undercooling and dendrite tip radius were presented. Some limitations and future developments of nonequilibrium theory were presented. (Edited author abstract) 55 Refs.

A New Modification to Shear Lag Model as Applied to Stiffness and Yield Strength of Short Fiber Reinforced Metal Matrix Composites

A new modification for the shear lag model is given and the expressions for the stiffness and yield Strength of short fiber metal matri×composite are derived. These expressions are then compared with our experimental data in a SiCw/Al-Li T6 composite and the published experimental data on different SiCw/Al T6 composites and also compared with the previous shear lag models and the other theoretical models.

Revision of a CCT Diagram of the Simulated ADI Weld Metal and Its Application in Actual Welding

A continuous cooling transformation (CCT) diagram of the simulated austempered ductile iron (ADI) weld metal has been developed by means of the Formastor-F diagram measurement apparatus, and revised by comparing with the actual welding. Finally, the revised diagram was used to determine the welding technology. (Edited author abstract) 4 Refs.

Microstructure and Properties of Spray Deposited 2024-20Si-5Fe Alloy

A rapidly solidified Al-Si-Fe-Cu-Mg alloy was prepared by spray deposition. The microstructure of the alloy includes silicon phase and delta -(Al,Fe,Si), Al//8Si//6Mg//3Fe, FeAl//2 and small FeSi//2 phases. The reasons of the formation of silicon and delta -(Al,Fe,Si) phase were analyzed. The tensile properties at the room temperature to 350 degree C were investigated, and the strengthening mechanism was suggested. The wear resistance and cutability of the alloy were measured as well. (Edited author abstract) 11 Refs.

Design and fabrication of soft X-ray multilayer for broadband reflection

A random method used for improving light throughput of a soft X-ray multilayer has been developed in the 18-20 nm spectral region, based on the traditional theory of periodic multilayer, and an 8% gain in integrated reflectance is obtained. The ensemble calculation is presented at the same time, and the multilayer is fabricated by magnetron sputtering.

Flexible unsmoothed cuticles of soil animals and their characteristics of reducing adhesion and resistance

Based on observing and analyzing the typical soil animals, the flexible unsmoothness is defined, which is the moving unsmoothness made by the flexible deformation of the structural units, and its characteristics of reducing adhesion and resistance is analyzed. The tests show that on the same conditions, compared with 45 Steel, the adhesion of the field_mouse’s fur is reduced by about 35%, its sliding resistance is reduced by about 80%.

Fe/Cu gradient composite materials prepared by laser sintering

USLNG CO2 laser beam as a heat source to sinter whole P/M （powder metallurgy） green com-pact is a new technique. As reported in refs. [1--4], the advantages of the laser sintering ofCu-base and Fe-base green compact were characterized by rapid sintering rate, no contamina-tion, fine structure and good properties.