Wei Fang Zhang

Research on Analytical Procedure of Failure Mechanism Consistency in Rubber Material Accelerated Ageing Test

This paper summarizes the advantages and disadvantages of existing analytical methods of failure mechanism consistency in the accelerated aging test at first. And then according to the characteristics of the rubber material, a kind of rubber failure mechanism consistency analytical method based on failure physics is offered by analyzing the thermal analysis curves.

Hygrothermal Behavior of T700 and T300 BMI Used for Advanced Polymeric Composite

The mechanism of hydrothermal ageing was investigated for T700/ BMI 5428 and T300/QY8911 by studying its glass transition temperature, tensile/compressive properties, changes of surface morphology absorbed in water with 100°C temperature. Results show that the glass transition temperature getting lower with the rate of water absorption. The tensile/compressive strength of composite decreased in the humid and heat environments, although with the identical failure mode.

Design of a Real-Time Device Monitoring Rubber Materials Compression Stress

Due to the complex operation of the compression stress relaxation test equipment used in the national standard, the measurement error is great and the uncertainty and instability of the test result is high, This paper proposes the design of a test equipment with the pressure transducer and digital indicator, which can do real-time monitor on the compression stress of rubber materials in accelerated ageing test. The stress range of the test equipment is 0～980 N, and temperature range 0～200°C. With this equipment, the compression stress in 70°C、80°C、90°C and 100°Cwas tested, and thus the curves of the compression stress at different temperature were obtained.

Fracture Analysis of the Tearing NBR Aged at Different Temperature

This paper analyzed the fracture of the tearing NBR 5621 samples under 500mm/min which had been respectively aged for 24 hours at the temperature of -45 °C, 25°C, 70°C and 120°C. It investigated the fracture characteristic of the tearing samples of NBR, which is flat and on it there are some step faceting. The fracture mechanism was also analyzed. The discussion illustrated that the ageing temperature influences the fracture appearance and has little effect on the fracture strength.

Experimental Study of Thermal Contact Conductance with Compensation Heater

This article describes an experimental setup to measure the TCC between interfaces of two contact solid materials. A new kind of design scheme of the compensation heater is put forward. An experimental investigation of thermal contact conductance is conducted with pressed pairs of GH4169 and K417 contacts in the range 130~280°C. The results show that TCC over this condition increases with temperature, but it is not monotonic. Moreover, the thermal contact conductance measured by experiment with compensation heater at the interface is higher than that without compensation heater.

Research on the Material Differences of 7050-T7451 Aluminum Alloy

Microstructure analysis and tensile fracture analysis were conducted on the domestic and imported 7050-T7451 aluminum alloy to investigate the material differences between them. Tensile test shows that the yield strength and tensile strength of domestic 7050-T7451 aluminum alloy are both higher than imported 7050-T7451 aluminum alloy, however, the material elongation and the reduction of area are both lower than imported material. Microstructure analysis shows that compared with domestic 7050-T7451 aluminum alloy, in the imported 7050-T7451 aluminum alloy, the degree of recrystallization and anisotropy is less, and the grain size is smaller. In addition, the transition from material surface to center organization of imported 7050-T7451 aluminum alloy is more smooth and uniform than domestic material. From tensile fracture analysis, it concluded that the domestic 7050-T7451 aluminum alloy has large grain size, low structural homogeneity, and little toughness characteristic of fracture, and those characteristics cause low elongation and low reduction of area of domestic 7050-T7451 aluminum alloy.

Study on New Structural Health Monitoring Sensor of Aircraft

Sensor is the core component of structural health monitoring system, which can collect the data of structural damage. The structural damage state can be gained after further processing. Aircraft serves in rigorous environment, and existing sensors cant meet the demand of its structural damage monitoring for inherent defect. A preparation method of partial poling piezoelectric film sensor was proposed in the paper, which can be used for structural damage monitoring of aircraft in combination with lamb wave.

The Methods of Corrosion Prediction for Materials in Natural Environment and their Applications

It is of great significance for corrosion prediction to avoid sudden accident, reduce casualties and environmental damage. This paper introduces the basic methods of corrosion prediction for the materials in natural environment. Firstly, statistical methods of corrosion prediction, including the linear extrapolation prediction method based on the function model and the extrapolation prediction method based on the related model, are showed. Then, some modern and mathematic methods for the corrosion prediction, such as grey forecasting method, prediction method of neural network, prediction method of pattern recognition, have been expounded. Finally, the typical applications in natural environment of those methods have been summarized.

The Research of Quantitative Analysis Methods of Composite Structure Repair Tolerance

In this paper, we researched the analysis methods of composite structure from a quantitative point of view. Based on reasonable assumptions, the research contents of the upper and lower repair tolerance were pointed. It was proposed that the remaining strength of damaged structural components should be used as the parameter index to analyze the lower repair tolerance, meanwhile calculating the parameter via the model of stress and interference. We could then confirm the conclusion by contrasting the references. To analyze the upper repair tolerance, we considered mainly technical level and economical efficiency, from which the upper limit could be ascertained.

Acoustic Emission Test for the Gradual Damage Process of Unidirectional Composites

The gradual damage progress of unidirectional laminate T700/ epoxy 6808 is investigated by acoustic emission test, and impact rate, impact amplitude, cumulative impact and impact energy in different test stages are measured. The results indicate that the sample suffers from diverse damage models in different loading stages. In the initial stage, damage mode is matrix crack, while other modes like matrix crack/ crack propagation, interface fracture and fiber breakage can be successively detected in the test.