Applied Mechanics and Materials Vols. 325-326

Abstract: It is required to characterize the materials according to the regulation in order to manufacture and fabricate components to be used for aircraft. The main purpose of this requirement is to determine the suitability of materials used for safe flight. Since the properties of composite materials are sensitive to the processing, characterization of composite materials has required very conservative methodology and therefore the whole process of characterization has been a redundant and time consuming process. This paper summarizes the efforts to adopt the composite materials characterization procedure for composite aircraft and provide the effective statistical methodology for evaluating composite materials manufacturing process. The result will be applied to the materials certification procedure for domestic composite materials for aircraft within the level of a global standard.

Abstract: Alignment of reinforcement particles was observed to affect the fatigue behaviors of extruded composites strongly. Micro-structure characterization showed a preferred orientation of the reinforcement particles parallel to the extrusion axis. As the reinforcement volume fraction increase, to some calculated values, the fatigue life and strength of the composite materials increases although the degree of particles alignment decreased.

Abstract: The influence of multi-component composite mineral admixtures on the mechanical properties and workability of concrete is studied in this paper, such as steel slag (SS), blast furnace slag (BFS) and fly ash (FA). Considering the above-mentioned factors, the optimal mixture ratio and substituted amount of composite mineral admixtures replacing equally cement are obtained. The results showed that composite mineral admixtures reduced the early compressive strength of concrete with composite admixtures, but significantly improved the workability and later compressive strength of concrete with composite admixtures. On the other hand, the optimal mixture ratio and substituted amount of double-mixing mineral admixtures are different.

Abstract: Shrinkage cracking is the direct cause which leads to the deterioration of durability and integrity of concrete. In this paper, ring-test methods are used to study the early age cracking characterization of compound mineral admixtures concrete which includes steel slag, blast furnace slag and fly ash. The effect of compound admixtures on cracking characterization of concrete is discussed, restraint stress caused by concrete shrinkage and cracking age are analyzed. Through the comprehensive consideration of the free shrinkage strain, creep, restriction factors on the effect of the cracking of concrete specimens. The results show that suitable proportion mineral admixtures can be used to reduce cracking in concrete. The risk of cracking can be estimated for compound admixtures concrete, so that it will improve the durability of concrete structures.

Abstract: Study on Strength design of steel components including residual stress. First, sample with residual stress of shot peening were detected, material properties change with residual stress was analyzed. And problems in the strength design were discussed. On this basis, design criteria for design of static strength and fatigue strength under plane stress state were derivated, the design criteria formula of the unification form is obtained. Finally, examples illustrate the reasonableness of the conclusions and deriving formulas.

Abstract: The mineral admixtures mixed into concrete have important effects on concrete performance. The workability and mechanical properties of the concrete are studied with different dosages of admixtures, such as steel slag powder, blast furnace slag powder and fly ash. The results show that fly ash has more advantages in improving the performance of the concrete. When steel slag powder, blast furnace slag powder and fly ash, respectively, replace the amount of cement to 30%, 30%, 20%, the mechanical properties of the concrete are improved significantly.

Abstract: The shrinkage cracking of concrete plays an important role to the accelerated deterioration and shortening the service life of concrete structures. The mineral admixture will be a perfect component of high performance concrete and its utilization will be a valuable resource for recycling. Early age cracking characteristics of concrete with compound admixtures, such as steel slag, blast furnace slag, fly ash, are studied in this paper using plate test method. The better anti-cracking performance of concrete will be realized when blast furnace slag replacing cement at 30%, steel slag and fly ash as the equal mixture components replacing cement at 30%, three kinds of admixtures replacing cement at 30% under the proper proportion.

Abstract: By adopting coating damage simulation method with electrochemical impedance spectroscopy, the influence of different damage degree K of grey chassis organic coating to its protective performance has been studied. The research found that electrochemical impedance spectroscopy could reflect the damage degree K of the coating. When K is less than or equal to 0.11, the coating still has prefect protective performance, when K is higher than or equal to 2.78, the protective performance of the coating is very low, and when K falls in between, the protective performance of the coating is just favorable; There exist a linear relationship between log (|Z|_0.1Hz) and log K, which may provide a theoretical basis to evaluate the protective performance of such kind of coatings.

Abstract: By adopting coating damage simulation research method with open circuit potential and electrochemical impedance spectroscopy, the influence of different damage levels of green organic composite coating to its protective performance has been studied. The research found that the variation of open circuit potential partly reflected the damage level of the coating. When K is less than or equal to 0.04, the coating still has favorable protective performance, while K is higher than 16, the protective performance of the coating is basically unavailable, but when K falls in between, the protective performance of the coating is fair good.

Abstract: To obtain complex shape alumina ceramic parts, a composite powder of epoxy resin binder E-06 and alumina powder were laser sintered combined with cold isostatic pressing (CIP). Experiments on selective laser sintering (SLS) and CIP were carried out to probe the influencing factors in the processes of forming alumina green parts. When laser power, scan speed, scan spacing and layer thickness were, respectively, 21 w, 1800 mm/s, 100 μm and 150 μm, the density and bending strength of alumina parts were relatively high. Following that, we experimented on different CIP maximum pressure which had different effects on densification of SLS alumina parts, the whole process in CIP was divided into two stages of I and II. Finally, the optimized SLS/CIP alumina parts were degreased and then sintered in 1600 °C for 2 h to produce crack-free alumina parts.