今日更新：International Journal of Solids and Structures 1 篇，Journal of the Mechanics and Physics of Solids 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 5 篇
International Journal of Solids and Structures
Harnessing unconventional buckling of tube origami metamaterials based on Kresling pattern
Emilio Turco, Emilio Barchiesi, Andrea Causin, Francesco dell’Isola, Margherita Solci
doi:10.1016/j.ijsolstr.2024.112925
利用基于克瑞斯林模式的管状折纸超材料的非常规屈曲
Kresling tube metamaterials are well known to exhibit a chirality-dependent exotic mechanical feature: a shortening or lengthening in the direction of the tube’s axis produces a relative rotation of the two polygonal bases of the tube. This property can be easily grasped by fabricating a single-storey Kresling tube using cardboard. What has not been stressed much, if not even recognized, in the literature is the fact that such a mechanical feature is not depending only on the (chiral) geometrical pattern and unaffected by the in-plane/bending stiffness of facets and the creases’ resistance to folding. Assuming to neglect the bending stiffness of facets, in the present contribution we prove, through some numerical simulations based on a discrete model taking into account inertial terms, that only when the in-plane-to-folding stiffness ratio is large the Kresling tube exhibits the aforementioned exotic feature as described in the literature. We also prove that a low in-plane-to-folding stiffness ratio reveals: (i) an unconventional buckling mode, both for axial shortening and lengthening, which resembles the mechanism of a camera diaphragm; (ii) a kind of auxetic behaviour, i.e. a stenosis in a shortening test.
Derivation, characterization, and application of complete orthonormal sequences for representing general three-dimensional states of residual stress
Sankalp Tiwari, Eliot Fried
doi:10.1016/j.jmps.2024.105729
用于表示一般三维残余应力状态的完整正交序列的推导、表征和应用
Residual stresses are self-equilibrated stresses on unloaded bodies. Owing to their complex origins, it is useful to develop functions that can be linearly combined to represent any sufficiently regular residual stress field. In this work, we develop orthonormal sequences that span the set of all square-integrable residual stress fields on a given three-dimensional region. These sequences are obtained by extremizing the most general quadratic, positive-definite functional of the stress gradient on the set of all sufficiently regular residual stress fields subject to a prescribed normalization condition; each such functional yields a sequence. For the special case where the sixth-order coefficient tensor in the functional is homogeneous and isotropic and the fourth-order coefficient tensor in the normalization condition is proportional to the identity tensor, we obtain a three-parameter subfamily of sequences. Upon a suitable parameter normalization, we find that the viable parameter space corresponds to a semi-infinite strip. For a further specialized spherically symmetric case, we obtain analytical expressions for the sequences and the associated Lagrange multipliers. Remarkably, these sequences change little across the entire parameter strip. To illustrate the applicability of our theoretical findings, we employ three such spherically symmetric sequences to accurately approximate two standard residual stress fields. Our work opens avenues for future exploration into the implications of different sequences, achieved by altering both the spatial distribution and the material symmetry class of the coefficient tensors, toward specific objectives.
High-cycle and low-cycle fatigue characteristics of multilayered dissimilar titanium alloys
Tianle Li, Wei Fan, Xifeng Li, Huiping Wu, Dayong An, Qi Hu, Jun Chen
doi:10.1016/j.ijplas.2024.104033
多层异种钛合金的高循环和低循环疲劳特性
Multilayered structures of dissimilar titanium alloys can achieve excellent fracture ductility and strength, while their fatigue characteristics especially dislocation networks and twin formation are rarely reported. Heterogeneous microstructures are observed in the multilayered TC4/TB8 alloys, including fine acicular α grains, continuous α layer at prior β grain boundaries (αGB) and β matrix on the TB8 layer, together with equiaxed α grains on the TC4 layer. High-cycle fatigue (HCF) and low-cycle fatigue (LCF) tests show that the initial fatigue damage appears at the αGB/β matrix interfaces on the TB8 layer instead of the boned TC4/TB8 interfaces. Since the stress concentration induced by dislocation pile-up is prone to micro-void formation and crack propagation at the αGB/β interfaces. For LCF, the αGB/β interfaces can not only act as impenetrable barriers and sources of lattice dislocations, but also allow the dislocations cross boundaries during cyclic tension and compression because of the high boundary energy. The formation characteristic of deformation twins that is beneficial for the plastic deformation of α grains in TC4 layer during cyclic strain is investigated. Furthermore, the hexagonal dislocation networks are also found within the equiaxed α grains of TC4 layer after LCF, and the role between interface barrier and slip direction in the formation mechanism is analyzed.
Seismic behaviour of reusable column base connection with pinned energy dissipators
MA Qi, CHAN Tak-Ming
doi:10.1016/j.tws.2024.112113
带有销钉消能装置的可重复使用柱基连接的抗震性能
A column base connection has been proposed to achieve reusability and self-centring after earthquakes. This proposed connection incorporates simple metallic yielding energy dissipators to effectively absorb seismic energy, while also employing pinned joints to facilitate the restoration of rocking behaviour in the column. To investigate the hysteretic behaviour of this innovative connection, a series of quasi-static tests were conducted on six groups of specimens. Among the parameters explored were the length, width, and limb number of the reduced section, activation angle, and material characteristics of the dissipative plate. During these experiments, the rocking mechanism was successfully demonstrated, and it was observed that the failure mode primarily involved concentrated plastic deformations of the dissipative plates. All of the specimens exhibited exceptional energy dissipation and self-centring capabilities. Furthermore, the repair process simply required the replacement of the damaged dissipative plates, which proved to be advantageous in terms of cost-effectiveness and efficiency. As a result, the repaired specimens regained their load-bearing ability and seismic performance to a comparable level as the original specimens. In the analysis of the test data, the changing patterns of dissipated energy, equivalent viscous damping ratio, and secant stiffness were determined in relation to the increasing target lateral displacement. The effects of various parameters on these aforementioned indexes were also preliminarily investigated. Additionally, based on the design concept, the relationship between moment and rotation angle of the column was described by an idealised curve. Consequently, the moment resistances of all test specimens were calculated, and the predicted results aligned well with the actual test results.
Seismic design-assisted-by-testing approach for racks with dissipative baseplates in the cross-aisle direction
Bonaventura Tagliafierro, Rosario Montuori, Ioannis Vayas
doi:10.1016/j.tws.2024.112126
跨通道方向带耗散基板机架的抗震设计辅助测试方法
A design-assisted-by-testing strategy is proposed for the upright frames of adjustable pallet racks. The methodology defines a procedure that aims to locate marked post-elastic behavior at the floor-to-upright connections of lateral resisting frames in the cross-aisle direction. Such connections are intended to enhance the performance of the cross-aisle frames when subjected to dynamic forces in their plane. The chosen baseplateis experimentally tested using monotonic and cyclic protocols at the Steel Structures Laboratory of the National Technical University of Athens (Greece). Then, a numerical model of the baseplate is calibrated using literature parameter definitions and hence validated using physical data. Additionally, the dynamic response of two upright frames is numerically investigated: one with traditional hinge connections and another with dissipative ones. This study indicates that the proposed procedure successfully enhances ductility, resulting in a significant reduction (up to 50%) in upright axial forces compared to the conventional configuration. Finally, the open-source code for ground motion selection, together with its database, is released.
An adaptive modeling method with a local choice of optimal displacement fields for finite element analysis of structures
Guoqiang Wei, Jeanne Paroissien, Pascal Lardeur, Frédéric Druesne, Marc Oujdene
doi:10.1016/j.tws.2024.112129
结构有限元分析中局部选择最佳位移场的自适应建模方法
In the standard finite element procedure, the user chooses himself which mechanical theory will be used for a given application. To this end, he relies on some rules acquired through experience or some theoretical consideration. But choosing an appropriate theory may be a difficult task when geometry, boundary conditions, loadings, and materials are complex. This paper aims to define an adaptive methodology to identify, in the context of linear static analysis, optimal finite element models from a theory choice point of view. A criterion is defined to choose, in each part of the structure, the relevant mechanical theory: solid, shell or beam. A solid mesh is defined for the whole structure while specific solid-shell or solid-beam approaches are used in shell or beam areas respectively. This avoids the construction of mid-surface or mid-axis geometries from solid ones, which is a complicated task, in particular for industrial applications. Kinematic relations between nodes are imposed to apply the displacement fields of shell or beam theories. This leads to a set of linear equations which are used for eliminating slave degrees of freedom. The methodology proposed can also be interpreted as a model size reduction method, compared to a complete solid approach. The effectiveness of this approach is demonstrated through two numerical examples, including academic cantilever structures and an industrial multilayered composite structure.
Non-stationary response analysis for sandwich panels with corrugated cores under moving random loads
Bo Li, Dong Shao, Yongqiang Tao, Ningze Sun, Hong zhang
doi:10.1016/j.tws.2024.112131
带波纹芯材的夹芯板在移动随机载荷作用下的非稳态响应分析
In this work, a recursion reverberation-ray matrix method (RRRM) is presented to formulate an exact and unified solution for the non-stationary responses analysis of the sandwich panels with corrugated cores (SPCC) subjected to the moving random loads. The governing equations for the basic units are obtained by employing the simple first-order shear deformation theory (S-FSDT) and Hamilton's principle. Then, based on the traditional reverberation ray matrix method (MRRM), the RRRM is established by incorporating a bidirectional recursion technique to effectively calculate the exact solutions of the whole model. Thereinto, the kinematic relation matrix between the cell units can be constructed to facilitate the coupling of various desired numbers of elements by employing the virtual coupling spring. In addition, a unified loading mechanism for multi-scenario loads is proposed by integrating the pseudo-excitation method (PEM) with the load stage division technique. The applicability and accuracy of the current method to non-stationary response behaviors of the SPCC are clarified by carrying out sufficient comparative studies between the calculated results with reference solutions from FEM and Monte Carlo simulation method. Furthermore, several meaningful conclusions are drawn regarding the effects of structural and load parameters on the vibration characteristic, non-stationary displacement response, power spectrum density (PSD), and time-varying root mean square (RMS).
Three-dimensional woven composites address the limitation of weak interlaminar strength found in traditional laminated composites and offer superior resistance to out-of-plane impact. However, the complex material composition and structural intricacies necessitate investigation into their damage mechanisms. This study introduces novel and reliable microscale and mesoscale Representative Volume Element (RVE) models for three-dimensional woven composites, developed through advanced CT scanning and comprehensive multi-directional tensile and shear experiments. The research explores the impact of fiber volume fraction on yarn mechanical properties using the microscale RVE model, yielding precise macroscale homogenization parameters through the mesoscale RVE model. Furthermore, a macro-meso model tailored for low-velocity impact scenarios is established, significantly enhancing computational efficiency without compromising accuracy, thus providing support for further research on the impact properties of three-dimensional woven composites.
