油气生成过程中黏土矿物的作用——基于矿物界面作用的思考

自20世纪40年代发现黏土矿物能够催化生油母质转化为石油(Grim,1947;Brooks,1949)以来,"油气生成过程中黏土矿物的作用"及其相关问题引起了石油地质学、矿物学和催化化学等多个领域的广泛关注。通过几代研究者们的努力,在地层矿物组成影响生烃机理、黏土矿物热解生烃机制等方面取得了丰富的研究发现(王行信,2006;袁鹏,2012)。然而,对油气生成中所涉黏土矿物微观

Localized coupling effects and multiphysics modeling for the laser ablation behavior of composite structure subjected to high speed airflow

When the composite structure is subjected to high power laser irradiation and high speed airflow, its ablation behavior presents significant localized characteristics and strong coupling effect. In this work, a coupled fluid thermal ablation model is developed to quantitatively investigate the localized coupling effects. Here a loosely coupled scheme with second order temporal accuracy is utilized to improve the coupling efficiency, and a high quality mesh reconstruction method combining the Arbitrary Lagrange Euler (ALE) algorithm and Radial Basis Function (RBF) interpolation algorithm is established to capture the moving boundary of the localized ablation pit with large deformation. The model is validated by simulating the laser ablation behavior of C/SiC composite plate subjected to the hypersonic airflow, and the predicted ablation pit profile shows a good agreement with the available experimental result. Analytical results show that as the evolution of the localized asymmetric ablation pit induces transformation of the flow regime from a closed pit flow to an open pit flow. Moreover, the flow regime transition would remarkably alter the localized flow characteristics, including the local static pressure and dynamic pressure, which in turn significantly affects the sublimation and mechanical erosion rates of C/SiC composite plate, respectively

高速气流对C/SiC复合材料激光烧蚀行为影响的实验研究

为了明确高速气流对C/SiC复合材料激光烧蚀行为的影响机制，开展了不同环境下强激光对C/SiC复合材料的烧蚀对比实验研究。利用激光器与高速风洞联合实验平台，完成了静态以及Ma 1.8,Ma 3.0,Ma 6.0气流环境下2D与3DN C/SiC复合材料激光烧蚀实验。结果表明，与静态环境相比，高速气流对C/SiC复合材料的激光烧蚀行为产生了显著的影响，气流的冲刷使得烧蚀坑呈现出更宽、更深、更光滑的变化趋势。随着气流速度的增长，线烧蚀速率与质量烧蚀速率逐渐增大，主要原因为当地静压降低引起的升华速率增大，以及动压增大引起的剥蚀速率增大。此外，通过实验对比了不同构型对C/SiC激光烧蚀行为的影响。结果表明：2D C/SiC复合材料由于厚度方向更低的导热能力、更低的孔隙率等原因，其在不同环境条件下抗烧蚀能力均强于3DN C/SiC复合材料

一种分析多材料结构激光烧蚀效应的方法和装置

 本申请实施例提供一种分析多材料结构激光烧蚀效应的方法和装置，该方法包括：建立多材料结构瞬态传热的有限元分析模型；利用ALE算法对有限元分析模型进行结构网格重构，并将变形前网格集合的温度场映射到变形后网格集合上，获得变形后网格集合的温度场；确定每个变形后网格对应的变形前网格；将每个变形后网格对应的变形前网格的材料编号确定为其对应的变形后网格的材料编号；利用变形后网格集合、变形后网格集合的温度场和变形后网格集合中每个变形后网格的材料编号对有限元分析模型进行更新；基于更新后的有限元分析模型，得到多材料结构的激光烧蚀效应的分析结果。本申请实施例能够实现激光对多材料结构烧蚀效应的高精度数值仿真分析

Experimental study of the high-power laser resistance of ablative material-filled sandwich panels with truss cores under hypersonic airflow

In this study, the performance of ablative material-filled sandwich structures with truss cores under laser irra-diation is experimentally analyzed in a hypersonic wind tunnel. As a comparison, we investigated the responses of a monolithic high-temperature alloy plate, unfilled sandwich panel, and thermal insulating material-filled sandwich panel. Failure times and ablation morphologies are assessed using a high-speed camera, while tem-perature histories are obtained using a colorimetric pyrometer. Experimental results show that, when subjected to a transverse hypersonic airflow, the laser resistance of the ablative material-filled sandwich structures is substantially better than that of other structures. Compared to a static environment, failure times of the sandwich structures in the hypersonic airflow are reduced due to the mechanical erosion effect. The detailed action mechanisms of the ablative material-filled sandwich structures are revealed by numerical modeling and the characterization of the ablation morphology

Large twist angle of a novel 3D lattice structure via a tailored buckling mode

A novel 3D centrosymmetric lattice that exhibits a large twist angle during compression is proposed by tailoring the twist buckling mode of a body centered cubic lattice and a simple cubic truss to the first. The imperfections of offset and multimaterial systems are introduced to control the twist direction. Effects of geometrical parameters and material properties on twist behavior are studied. Results suggest that the buckling driven lattice configuration can twist at an angle of 100 degrees and an average angle per unit axial strain of 6.7 degrees/%. The novel configurations can be used as force switches, safety devices, and temperature controlled transmission devices

Compression performances and failure maps of sandwich cylinders with pyramidal truss cores obtained through geometric mapping and snap-fit method

The compressive behaviors and failure maps of lightweight all-metallic sandwich cylinders with pyramidal truss cores are studied experimentally and theoretically. Orthotropic truss cores are fabricated through geometric mapping and snap-fit method. Curved facesheets are bonded to the truss cores by two-times vacuum brazing approach to eliminate unbound nodes. The full-field deformation and strain of the sandwich cylinder are measured by using the 3D digital image correlation system. The local buckling of the facesheet, the mode of which is influenced by the truss cores, is observed during the experiment. Theoretical models are developed considering five possible failure modes of the sandwich cylinder under compression, namely, Euler buckling, global buckling of the cylinder, local buckling of facesheet, face yielding and core member buckling. Failure maps are constructed on the basis of the models. The typical failure modes obtained from numerical simulation are consistent with the theoretical prediction