Advanced Materials Research Vols. 1030-1032

Abstract: With the development of advanced composites technology, composites instead of traditional aluminum alloy, will be widely used to build full-size aircraft windshield structure in the aviation field. The finite element model of commercial aircraft composite windshield is established in the environment of Msc.Patran / Nastran. And based on Tasi-Wu failure criterion, the strength of windshield structure under typical load pressure is predicted and analyzed during failure processes. It shows that composite windshield can work better through rational design according to the analysis result.

Abstract: The dynamic response of the SFRHSC wall under blasting load is simulated and analyzed by establishing the 1/4 wall model with finite element explicit dynamic analysis software ANSYS/ls-dyna. Considering the damage and strain rate effect, the J-H-C model is used as material model, and model parameters are calculated by using the test of literature data. The explosion loaded by CONWEP model and *LOAD_BLAST keyword. Different failure modes of wall under different scaled distances are analyzed, the results show that shear failure will occur when the scaled distance is small, flexure failure will happen when the scaled distance is large, in addition, comparing with normal reinforced concrete, the displacement in the center of the SFRHSC wall is smaller under the same condition, which embodied that the high tensile strength and compressive toughness of SFRHSC are significantly enhanced the anti-explosion ability of the wall. The research results of this article can provide reference for the design of SFRHSC fender wall.

Abstract: This article deals with thermal insulation sandwich materials and with their flexural properties. Suitability of designed testing method is confirmed according to experimental research. According to proposed method, flexural properties such as flexural strength and modulus of elasticity are stated. Type and mechanism of destruction sandwich materials during tests are described also.

Abstract: Due to the internal structure of red sandstone is loose, the influence factors of acoustic velocity are variety, it is necessary to make a quantitatively research on the influence factors. With the aid of the ultrasonic testing for the rock, p-wave velocity of red sandstone decreased with the increase of porosity under the condition of no coupling medium, when the porosity exceeded a certain value, its internal pores and fractures had a great influence on wave velocity. When the density of red sandstone was greater than 1.82 g/cm³, wave velocity changed little, while the density was less than 1.82 g/cm³, wave velocity decreased rapidly. Under water-solid coupling condition, the change of wave velocity and porosity had no obvious regularity, part of the specimens’ wave velocity decreased a bit, while some specimens’ wave velocity were slightly higher, but the amplitude were small; Under oil-solid coupling condition, longitudinal wave velocity changed significantly, the biggest percentage of increase was 46.3%, the average was 33%.

Abstract: Usually, a large horizontal force will be generated to the pier in the construction process, which may induce significant influence on the pier‘s safety, especially in the case of the bridges with high piers and long span. Some cracks ermerged in the foot part of a pier in the construction stage and a horizontal force was believed to have been load on it, hence its reliability was douted.The pier was simulated with virtual laminated element program, and its mechanical performance under a horizontal force was calculated with both geometrical and material nonlinearity are considerd, thus its whole loading and failure process was illustrated and the pier’s safety was assessed.

Abstract: On the background of Jiangxi Wuning–Ji'an highway tunnel, the rock triaxial rheological testing machine is adopted to conduct hierarchical incremental cyclic loading and unloading rheological tests on class II, class III, and class IV rock on the tunnel site. Take class II and class IV surrounding rock for example, this paper analyzes the creep deformation rules over time in depth, studies rock rheological properties, and provides the best rheological model of tested rock. According to research findings, deformation of class II and class IV surrounding rock is composed of instantaneous elastic deformation and creep deformation. The instantaneous elastic strain value increases with the increasing stress level and the rock deformation manifests as brittle failure. The generalized Kelvin model is the best rheological model that describes deformation of class II and class IV surrounding rock.

Abstract: The artificial island ground on an open sea is covered by thick soft soil. It must be improved before using. In accordance with a designing scheme, the ground treatment method is inserting drain boards on land and jointed dewatering surcharge preloading, the residual settlement is not more than 30cm after improvement and the average consolidation degree is more than 85%. In order to estimate ground improvement effect and construction safety, instruments are buried to monitor the whole ground improving processes. By monitoring settlement and pore water pressure, it is shown that the total ground settlement in construction is 2234mm, its final settlement is 2464mm, and consolidation degree and residual settlement respectively satisfy requirements. In ground improvement, horizontal displacement is small and construction is safe. Meanwhile, the results of soil properties and vane shear strength detection tests show the soft soil ground is greatly reduced in water content and porosity ratio, and improved in strength. It is named that the ground improvement method is reasonable and reaches expected effect.

Abstract: Taking Yuzhen Palace of Wudang Mountain integrally jack-up engineering for instance, the paper analyzes the stress change of the joist in different of jacking and monitor point arrangement using finite element method. By changing the distance and the number of jacking points, the stress distribution of joist is analyzed, so that it concludes a reasonable layout scheme. And the results show that: the jacking and monitor points position have an influence on the stress of joist in the process of jack-up. Reasonable arrangement of jacking and monitor points could effectively reduce the additional internal force of joist to coordinate each point jacking force and rational allocation of jack.

Abstract: Mechanical properties of CA mortar with different air content were studied, and the size of the air bubbles was also analyzed. Results showed that the ductibility of CA mortar could be largely prolonged by the air bubbles. As the air content of CA mortar increased from 4.2% to 9.1%, the strain of the maximum stress increased from 1% to 2%. The compressive strength and elastic modulus of CA mortar decreased as the air content increased. And when the air content of CA mortar was higher than 15%, the compressive strength of it decreased rapidly. The SEM analysis showed the air bubbles of diameter larger than 0.5mm was the primary reason of decrease of the compressive strength.

Abstract: This paper presents digital models of indirect tensile test and four point bending fatigue test for asphalt mixture at a microstructural level. Conventional images were converted into Finite Element (FE) models which consist of the information of material heterogeneity and microstructures of real asphalt mixtures. It was found that the material heterogeneity especially the volumetric properties can significantly affect the fatigue behavior which is quite different from the traditional findings based on the hypothesis of homogeneous material. The results show that the proposed method for FE model of fatigue test can be extended for other analyses like rutting or low temperature cracking.