力学进展

DEVELOPMENT OF NUMERICAL SIMULATION FOR VISCOELASTIC FLUID FLOW

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2001, 31(2): . doi: 10.6052/1000-0992-2001-2-J2000-029

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2001, 31(2): . doi: 10.6052/1000-0992-2001-2-J2001-033

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PROGRESSING IN THE STUDY ON MECHANICAL PROPERTIES OF 3D WOVEN COMPOSITES

2001, 31(2): 161-171. doi: 10.6052/1000-0992-2001-2-J1999-055

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Recent research developments on mechanical behaviours of 3D woven composites are reviewed. It is shown that the mechanical properties of 3D woven composites depend not only on the respective properties of the constituent fiber and matrix but also on the goemetric structure of the 3D reinforcement. The relationship between mechanical properties of 3D woven composite and micro-structure of the reinforcement is discussed, especially the geometric pattern of the filament bundle and the shape of its cross section within the 3D reinforcement, which play an important role in determining the performance of the woven composites. Experiment investigations concentrate on the observations and analyses of the damage mode of 3D woven composite and the effects of the 3D reinforcement in preventing the propagation of micro-cracks inside the material. Modeling techniques are applied successively, based on the lamina theory, average orientation model and finite element analysis, to investigate the elastic properties of 3D woven composite. However, further work is still required before the strength and damage of the 3D woven composites can be properly predicted. Some suggestions for further investigations are also made in this paper.

NUMERICAL METHODS FOR INVERSE PROBLEMS IN ELASTIC DYNAMICS

2001, 31(2): 172-180. doi: 10.6052/1000-0992-2001-2-J2000-050

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The numerical methods for inverse problems in elastic dynamics are introduced in this paper. These methods include linear inverse methods under some approximation, non-linear iterative inverse methods in time domain or in frequency domain, optimizing method with deterministic or non-deterministic searching in the solution space, homotopy methods that converge in a large domain and multi-scale inverse methods composed of multigrid and wavelets. The principle, characteristics and limits of thes emethods are analyzed and the further research of numerical inverse methods in the future are discussed.

A REVIEW ON STRUCTURAL DYNAMIC OPTIMUM DESIGN

2001, 31(2): 181-192. doi: 10.6052/1000-0992-2001-2-J1999-085

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Structural dynamic optimum design is an advanced subject in the field of engineering structure design at present. In this paper, the developments of structural dynamic optimum are reviewed on the following four subjects, namely, structural dynamic characteristics, dynamic response, dynamic sensitivity analysis and optimization design based on reliability. Finally, the future trends of structural dynamic optimization are discussed.

PROGRESS OF THE FATIGUE DAMAGE CUMULATIVE RULES OF FRP

2001, 31(2): 193-202. doi: 10.6052/1000-0992-2001-2-J1999-024

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In this paper the fatigue damage cumulative rules of fibre-reinforced plastics (FRP) are reviewed and discussed. These rules can be classified as the residual life model, residual strength model, residual stiffness model, dissipational energy model, Markov-chain model and other empirical models. Two sets of experimental data have been employed for the comparison between experiment and prediction given by different models. The results show that the prediction capacity of the models is not better than that of the traditional Miner rule, with the model presented by Yao and Himmel little better than others.

ADVANCES IN ULTRASONIC CYLINDRICAL GUIDED WAVES TECHNIQUES AND THEIR APPLICATIONS

2001, 31(2): 203-214. doi: 10.6052/1000-0992-2001-2-J2000-018

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The recent research advances in ultrasonic cylindrical guided waves techniques and their applications in the field of NDT are briefly reviewed. An introduction on the concepts of guided waves and their characteristics is given. The choices of the modes of guided waves and exciting frequency, the methods of exciting and receiving guided waves, the interaction of guided waves with defects, the methods of signal processing and the possible applications in NDT are reviewed.

APPLICATION OF LARGE EDDY SIMULATION TO TURBULENT COMBUSTION

2001, 31(2): 215-226. doi: 10.6052/1000-0992-2001-2-J1999-037

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As an effective method for study of turbulent flow and turbulent combustion, large eddy simulation (LES) is widely used in recent years. The most challenging problem in LES is how to build a proper subgrid scale model. Based on the review of the basic idea and implementation of LES, several subgrid scale models of turbulent flow and turbulent combustion are discussed in this paper. Some researchers' examples of LES of turbulent combustion are given in order to show the successful application of LES to the study of turbulent combustion. This paper points out the importance of LES in numerical simulation of turbulent combustion and provides references for development and application of large eddy simulation to turbulent combustion.

NUMERICAL SIMULATION OF SEPARATION AND VORTICAL FLOWS ON DELTA WINGS

2001, 31(2): 227-244. doi: 10.6052/1000-0992-2001-2-J1999-108

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The progress in numerical simulations of separation and vortical flows on delta wings (including double-delta wings, strake-delta wings and close-coupled canards) was summarized in this paper. The numerical methods using Euler equations and N-S equations in the simulations for the configurations of complex vortical flows and structures of separation flows on different delta wings under the conditions of different angle of attack and flow M numbers are reviewed. The effects of control equations, grids, turbulence model and numerical methods on the results were also discussed.

HIGH ORDER, HIGH RESOLUTION FINITE VOLUME METHODS FOR HYPERBOLIC CONSERVATION LAWS

2001, 31(2): 245-263. doi: 10.6052/1000-0992-2001-2-J2000-031

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Finite volume method is a numerical method that discretizes the conservation laws in the integration form. It combines the merit of the finite element method with that of the finite difference method. Now finite volume methods on unstructured meshes are very popular in CFD because of the geometric flexibility and adaptivity of computational grids. In this paper, we review the development of high order, high resolution finite volume methods for 2-D hyperbolic conservation laws.

AN EXTENSIVE REVIEW ON MESO-DAMAGE EVOLUTION IN POLYMERS

2001, 31(2): 264-275. doi: 10.6052/1000-0992-2001-2-J2000-002

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The crazing damage and fracture process of polymers is very complicated and important. The thermodynamic or mechanical conditions and micromechanisms of craze initiation in polymers are briefly introduced in this paper. The recent advances in experimental studies and model computations, the meniscus instability mechanism for craze-tip advance, the creep mechanism and surface-drawing mechanism for craze thickening are discussed in detail. The cross-tie fibrils in craze microstructure, the relations between the molecular weight, entanglement density and the craze fracture behavior and the interaction between craze and crack growth are extensively reviewed. It is pointed out that the further studies on craze growth and breakdown can be expected to relate the macroscale fracture toughness, mesoscale structures and microscale material parameters, thus provide guidance to design the material toughness at microscale level. Meanwhile, the further study and development trends of this field are also outlined.

2001, 31(2): 303-303. doi: 10.6052/1000-0992-2001-2-J2001-032

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2001 Vol. 31, No. 2

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