基于导重法构建了惯性载荷作用下的多材料结构拓扑优化数学模型,在体积约束下使得其结构柔度最小.将多材料拓扑优化问题分解为一系列单材料拓扑优化问题,采用材料属性有理近似模型(Rational Approximation of Material Properties,RAMP...基于导重法构建了惯性载荷作用下的多材料结构拓扑优化数学模型,在体积约束下使得其结构柔度最小.将多材料拓扑优化问题分解为一系列单材料拓扑优化问题,采用材料属性有理近似模型(Rational Approximation of Material Properties,RAMP)来表达密度与弹性模量间假定的非线性函数关系,利用导重法建立惯性载荷下设计变量的迭代表达式并通过数值算例验证导重法在考虑惯性载荷作用下多材料结构拓扑优化的有效性.算例结果表明:RAMP插值方法相比其他常用插值模型得到的拓扑构型更清晰,灰度单元更少,在算例1的对比中结构柔度最高降低了35.2%.受惯性载荷影响越大的设计区域其分布的材料弹性模量越大,且高模量密度比能够显著提升结构刚度.展开更多
The crashworthiness is an important design factor of civil aircraft related with the safety of occupant during impact accident. It is a highly nonlinear transient dynamic problem and may be greatly influenced by the u...The crashworthiness is an important design factor of civil aircraft related with the safety of occupant during impact accident. It is a highly nonlinear transient dynamic problem and may be greatly influenced by the uncertainty factors. Crashworthiness uncertainty analysis is conducted to investigate the effects of initial conditions, structural dimensions and material properties. Simplified finite element model is built based on the geometrical model and basic physics phenomenon. Box-Behnken sampling and response surface methods are adopted to obtain gradient information. Results show that the proposed methods are effective for crashworthiness uncertainty analysis. Yield stress, frame thickness, impact velocity and angle have great influence on the failure behavior, and yield stress and frame thickness dominate the uncertainty of internal energy. Failure strain and tangent modulus have the smallest influence on the initial peak acceleration, and gradients of mean acceleration increase because the appearance of material plastic deformation and element failure.展开更多
An integrated design concept for crashworthy fuselage using sine-wave beam and strut is proposed and investigated. The finite element model of aircraft fuselage is built first. The structures above cabin floor, occupa...An integrated design concept for crashworthy fuselage using sine-wave beam and strut is proposed and investigated. The finite element model of aircraft fuselage is built first. The structures above cabin floor, occupant and seat are simplified as two rigid blocks. The fuselage frame is rede- signed, and the sine-wave beam is arranged under the frame. The impact dynamic performance of the aircraft with bottom sine-wave beam structure is studied and compared with that of conven- tional type. To obtain better crashworthiness performance, different rigidity of strut is combined with the sine-wave beam bottom structure. Numerical simulation result shows that the proposed sine-wave beam bottom structure could not only dissipate more proportion of impact kinetic energy but also reduce the initial peak acceleration. The structure and rigidity of strut have great influence on the crashworthiness performance. To give a better fuselage structure, both of the strut and bottom structure should be properly integrated and designed.展开更多
文摘基于导重法构建了惯性载荷作用下的多材料结构拓扑优化数学模型,在体积约束下使得其结构柔度最小.将多材料拓扑优化问题分解为一系列单材料拓扑优化问题,采用材料属性有理近似模型(Rational Approximation of Material Properties,RAMP)来表达密度与弹性模量间假定的非线性函数关系,利用导重法建立惯性载荷下设计变量的迭代表达式并通过数值算例验证导重法在考虑惯性载荷作用下多材料结构拓扑优化的有效性.算例结果表明:RAMP插值方法相比其他常用插值模型得到的拓扑构型更清晰,灰度单元更少,在算例1的对比中结构柔度最高降低了35.2%.受惯性载荷影响越大的设计区域其分布的材料弹性模量越大,且高模量密度比能够显著提升结构刚度.
基金supported by the Postdoctoral Science Foundation of China (Nos. 2012M510306, 2013T60054)
文摘The crashworthiness is an important design factor of civil aircraft related with the safety of occupant during impact accident. It is a highly nonlinear transient dynamic problem and may be greatly influenced by the uncertainty factors. Crashworthiness uncertainty analysis is conducted to investigate the effects of initial conditions, structural dimensions and material properties. Simplified finite element model is built based on the geometrical model and basic physics phenomenon. Box-Behnken sampling and response surface methods are adopted to obtain gradient information. Results show that the proposed methods are effective for crashworthiness uncertainty analysis. Yield stress, frame thickness, impact velocity and angle have great influence on the failure behavior, and yield stress and frame thickness dominate the uncertainty of internal energy. Failure strain and tangent modulus have the smallest influence on the initial peak acceleration, and gradients of mean acceleration increase because the appearance of material plastic deformation and element failure.
基金co-supported by the National Natural Science Foundation of China(No.11402011)the Fundamental Research Funds for the Central Universities
文摘An integrated design concept for crashworthy fuselage using sine-wave beam and strut is proposed and investigated. The finite element model of aircraft fuselage is built first. The structures above cabin floor, occupant and seat are simplified as two rigid blocks. The fuselage frame is rede- signed, and the sine-wave beam is arranged under the frame. The impact dynamic performance of the aircraft with bottom sine-wave beam structure is studied and compared with that of conven- tional type. To obtain better crashworthiness performance, different rigidity of strut is combined with the sine-wave beam bottom structure. Numerical simulation result shows that the proposed sine-wave beam bottom structure could not only dissipate more proportion of impact kinetic energy but also reduce the initial peak acceleration. The structure and rigidity of strut have great influence on the crashworthiness performance. To give a better fuselage structure, both of the strut and bottom structure should be properly integrated and designed.
