Principles of Optimization of Structures Against an Impact

Abstract

We discuss principles of design of optimal structure subjected to a dynamical load. The goal is to design a structure which is capable of sustaining an impact of a dynamical load (collision or blast) by absorbing and redistributing the energy of the collision and keeping the structural integrity. An unstructured material can absorb energy until it melts. However, a tiny portion of this energy yields to a construction's disintegration due to instability of the damage that leads to energy concentration. Appearance of concentrated damage zones, such as cracks or delaminating, destroys the construction. The remains of the disintegrated construction still can absorb a lot of energy. The goal of optimal design is to maximally use the ability of a damageable material to absorb energy. We develop a theory of macro-and micro behavior of damageable structures. Damage is understood as a process of irreversible phase transition from initial to damaged state. The wave of phase transition is described and the structural parameters are optimized. We propose a concept of a replaceable protective structure design. Such structure should dissipate maximum energy, be able to spread energy of damage, and the damage process should be as stable as possible. An optimized structure should trigger stress waves propagation and thereby spread the stress more evenly; it must also contain multiple energy absorbers. This can be achieved by the use of a composite with a special structure made of a strong frame, and an absorbing filler material. The absorbing rate and rate of damage propagation are times amplified by waiting-link structures that we describe below. The optimization strategy requires a proper choice of design parameters. They are: the shape of the whole protective construction, location of beams or frames and waiting links, and the choice of materials in the structure and in the outer layers.

Machine learning-based optimization design of bistable curved shell structures with variable thickness

“…2(d), it is proved that the curved shell under the same material and quality can change its mechanical properties by changing its thickness distribution, including the backward snapping force of the research object in this paper. Therefore, the backward snapping force of re-entrant structure is determined as a function of variables ti , [i=1, 2, 3, ..., 19,20], this function will be determined by the ML model constructed below.…”

“…Each curved shell has 20 sections while each of which has 11 possible relative thicknesses. There are 11 20 possible combinations. This is already a design space close to infinity.…”

“…Compared with curved beams, curved shell structures have some similar or even better mechanical properties [14], such as negative stiffness [15,16], multi-stability [17][18][19], and excellent energy absorption [20][21][22][23]. Over the past few decades, & These authors contributed equally to this work and should be considered co-first authors 2 / 20 significant efforts have been devoted to the approximate theoretical analysis, numerical simulations, and experimental investigations of the mechanical properties of shell structures [24][25][26], among them, Civalek et al have made great contributions to solving the motion control differential equations of shell structures, using a series of numerical analysis methods including Generalized Differential Quadrature(GDQ) [27], Discrete Singular Convolution(DSC) [28,29], DSC-Differential Quadrature (DQ) coupling method [30] and higher-order shear-normal deformation theory and analytical approach to the static analysis, etc.…”

Fault-tolerant elastic–plastic lattice material

“…A helicoidal structure with increasing energy absorption was suggested in [17]. The designs of impact-protecting structures with waiting links were described in [18,19].…”

Анализ Возможности Использования Противоударных Структур В Авиационной Технике

“…На основании данного анализа нами сформулирована гипотеза о перспективности создания материалов на основе арамидных тканей, которые имеют области динамического и фрикционного взаимодействия нитей, т. е. «дискретных» материалов.Перспективными направлениями являются создание защитных структур на основе максимального использования энергетической поглотительной способности разрушаемого материала[6] и использование новых материалов, в частности современных полимеров. Во всех неструктурированных материалах скорость напряжения уменьшается с увеличением деформации из-за развития дефектов, открытия микротрещин и других механизмов.…”