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
Modified vibro-acoustic spectrum characteristics for underwater cylindrical shells with mechanical metastructures
Yaoze Zhuang, Deqing Yang, Qing Li, Xiaoming Geng
doi:10.1016/j.ijsolstr.2025.113219
具有力学元结构的水下圆柱壳的改进振声频谱特性
The vibro-acoustic spectrum characteristics for underwater thin-walled structures continue to attract attention. This study presents a load-bearing, wide-bandgap metastructure for modifying vibro-acoustic spectrum characteristics of a cylindrical shell. Initially, methods for calculating and evaluating the load-bearing capacity and bandgap characteristics of unit cells are established. Subsequently, an annular metastructure is configured in a cylindrical coordinate, broadening the bandgap and the range of radiated noise suppression through compound unit cells. Finally, by localized mass and reinforcement, the enhancement of macroscopic structural load-bearing capacity and the modified spectrum characteristics are achieved. This study provides a cylindrical shell in which internal vibration transmits through the flange to the shell and then generates radiated noise. The sound power of the assemblywhich is equipped with either the original support or the metastructures was obtained through experiments and simulations. The experimental study demonstrated a 3.1 dB noise reduction across a broad frequency range from 824 Hz to 1500 Hz, with over 50 % of the frequency characteristics significantly altered. Furthermore, the metastructure achieved a weight reduction of 2.16 kg compared with the original configuration. This study not only achieves the evaluation of the load-bearing capacity of the microscopic unit cell but also realizes the amplitude suppression and spectrum modification of radiated noise for underwater cylindrical shells.
Enhancement of adhesion strength through microvibrations: Modeling and experiments
Michele Tricarico, Michele Ciavarella, Antonio Papangelo
doi:10.1016/j.jmps.2024.106020
通过微振动增强附着力：建模和实验
High-frequency micrometrical vibrations have been shown to greatly influence the adhesive performance of soft interfaces, however a detailed comparison between theoretical predictions and experimental results is still missing. Here, the problem of a rigid spherical indenter, hung on a soft spring, that is unloaded from an adhesive viscoelastic vibrating substrate is considered. The experimental tests were performed by unloading a borosilicate glass lens from a soft PDMS substrate excited by high-frequency micrometrical vibrations. We show that as soon as the vibration starts, the contact area increases abruptly and during unloading it decreases following approximately the JKR classical model, but with a much increased work of adhesion with respect to its thermodynamic value. We find that the pull-off force increases with the amplitude of vibration up to a certain saturation level, which appeared to be frequency dependent. Under the hypothesis of short range adhesion, a lumped mechanical model was derived, which, starting from an independent characterization of the rate-dependent interfacial adhesion, predicted qualitatively and quantitatively the experimental results, without the need of any adjustable parameters.
A polycrystalline elastic-plastic phase field model is proposed to reveal the mechanisms of secondary crack initiation, propagation and closure during the water quenching process in medium-carbon martensitic steel. The formation of martensite variants during the quenching process is considered in our model. Moreover, this model can account for the influence of the elastic stress and plastic strain generated after the martensitic transformation during the quenching process on the fracture process. The simulation results show that secondary cracks initiate at the grain boundary region near the primary crack due to its induction. Additionally, they can also initiate at multiple locations in the high-angle grain boundary regions far from the primary crack. This occurs due to elastic stress concentration and plastic strain localization in these regions. Then secondary cracks mainly propagate along prior austenite grain boundary areas. The tensile stress on both sides of the crack tip is the main driving force for crack initiation and propagation. As the external loading increases, the stress at the crack tip gradually transitions into compressive stress, ultimately leading to the closure of the crack in the grain boundary regions. More importantly, these propagation paths of secondary cracks are consistent with the experimental results. Compared with intracrystalline defects, grain boundary defects are more likely to induce crack initiation and propagation. Therefore, this model can offer theoretical guidance for solving the issue of water quenching cracking in medium-carbon martensitic steel.
Topology-optimized multimaterial 4D-printed Fabry–Perot filter with enhanced thermal stability using two-photon polymerization
Johnny Moughames, Julio A. Iglesias Martínez, Gwenn Ulliac, Thibaut Sylvestre, Antoine Barbot, Jean-Claude André, H. Jerry Qi, Frédéric Demoly, Muamer Kadic
doi:10.1016/j.tws.2024.112900
拓扑优化的多材料4d打印法布里-珀罗滤波器，利用双光子聚合增强热稳定性
Tailoring material properties at the microscale is essential for advancing technologies, particularly in the field of 4D printing. The ability to manipulate thermal expansion is particularly critical for opto-mechanical systems, where precise deformation control is required. This paper introduces a novel approach that combines 4D printing with topology optimization to design and fabricate a multimaterial structure capable of mitigating undesired thermal expansion upon heat stimulation. This approach is applied to the development of a microfabricated Fabry–Perot filter as a robust alternative to directly printed cavity-based devices. Employing both approaches enables the determination of material distribution within the internal geometry of the structure, resulting to a temperature-insensitive response while maintaining optical performance. Using two-photon polymerization, the designed structure is 3D-printed with a combination of active and passive materials to achieve a controlled geometry. The final structure demonstrates a minimal change in dimensions under a temperature increase, confirming its ability to counteract thermal expansion effectively. This work showcases the potential of 4D printing and intelligent design strategies for developing devices at the microscale with precise thermal control.
A time variational method for computing nonlinear normal modes of a thin highly flexible cantilever beam and its experimental evaluation using phase resonance approach
Renjith A R, I R Praveen Krishan
doi:10.1016/j.tws.2025.112910
一种计算高柔性悬臂梁非线性正态模态的时变方法及其用相位共振法的实验评价
This work studies the nonlinear free vibration characteristics of a thin, long, and highly flexible cantilever beam of aspect ratio 644:1 (with length 0.95 m) using the evaluation of nonlinear normal modes. The nonlinear normal modes of the beam are evaluated experimentally from the free decay response after the nonlinear normal mode appropriation using the phase resonance approach satisfying the appropriation criteria. The beam is modeled for computations using gradient-deficient beam elements of Absolute Nodal Coordinate Formulation with bending deformation defined using curvature terms to incorporate the rigid body motions. The degrees of freedom of every element have nonlinear terms associated with them due to the highly coupled system matrices. Therefore, the Time Variational Method is used to extract nonlinear normal modes to ease the requirement of domain transformation for nonlinearity handling, in contrast to other solution techniques. The comparison of results shows that they agree with each other. The first nonlinear normal mode appropriated response shows the presence of super-harmonics both experimentally and computationally. The experiments show no significant softening or hardening behavior of the beam near the first nonlinear normal mode, while the computations show a slight hardening behavior. The appropriate response shows the presence of sub-harmonics and super-harmonics for the second nonlinear normal mode. Both experiments and computations could predict the softening behavior associated with the second nonlinear normal mode. At higher energy levels, there is a transition in the mode shapes for the second nonlinear normal mode, and even a chaotic behavior was observed.
Hypervelocity impact (HVI) of space debris poses significant challenges to spacecraft in orbit, requiring materials that can withstand extreme conditions. In order to investigate the effect of particle content on the damage behavior of the B4C ceramic particle((B4C)p) reinforced 2024Al matrix composite ((B4C)p/2024Al) bumpers during HVI events, lightweight (B4C)p/2024Al-T6 composites with varying volume percentages (30 vol.%, 50 vol.%, and 70 vol.%) were fabricated using pressure infiltration technology. With the help of the two-stage light-gas gun, HVI experiments ranging from 3 to 5 km/s were conducted on Whipple shields with 2024Al(T6) and (B4C)p/2024Al-T6 composite bumpers using 6.35 mm diameter 2017Al(T4) spherical projectiles. Furthermore, the movement process of bumper debris clouds was captured using the Flash X-ray high-speed photography system. The HVIs of the (B4C)p/2024Al-T6 composite bumper were simulated using the microstructure SPH bumper model. Based on the macro and micro damage features observed in experimental bumpers and simulation results, the damage and the hole formation process of (B4C)p/2024Al-T6 composite bumpers induced by the spherical projectile impact were discussed. Increased particle content attenuates the shock wave intensity and diminishes the damage area around the impact point of the composite bumper, reducing the clear hole diameter when the bumper is impacted at relatively close velocities. This increase in particle content also significantly reduces the spall strength of the composite. The adiabatic shear of the aluminum alloy and the fragmentation of B4C particles facilitate crack initiation and propagation within the composites, thereby promoting the hole formation under HVIs. This study demonstrates that particle content can influence the damage behavior of the (B4C)p/2024Al-T6 composite under HVI and thus affecting its impact resistance.
In recent decades, noise pollution and electromagnetic radiation have emerged as the two primary sources of global public hazard. In order to offset the detrimental impact of these pollutants on industrial output and human wellbeing, a metastructure that is capable of simultaneously fulfilling the functions of electromagnetic dissipation and noise absorption is proposed. The non-local lightweight multifunctional metastructure (MFMS), designed through an integrated material-structure-functionality approach, simultaneously enables broadband sound absorption and electromagnetic dissipation. The MFMS achieves an acoustic absorption of approximately 0.8 within the frequency range of 500 Hz to 1,000 Hz. Moreover, the MFMS displays an electromagnetic reflectivity below -10 dB across the majority of the frequency range of 2-40 GHz. The experiment and simulation reveal that the broadband sound absorption mechanism is based on the structural impedance match and parallel operation of multiple resonance modes. In contrast, the mechanism of electromagnetic dissipation is a consequence of the combined influence of structural impedance matching and dielectric loss principles. Overall, an innovative multi-objective optimization method is proposed to design the MFMS.
Nonlinear functionally graded metamaterials for hydrogen storage and enhanced sustainability under extreme environments
P. Tiwari, S. Naskar, T. Mukhopadhyay
doi:10.1016/j.tws.2024.112901
用于储氢和增强极端环境下可持续性的非线性功能梯度超材料
Functionally graded materials can exhibit remarkable tolerance towards extreme hot or cold environments and chemical surface degradation. This article exploits such properties of functionally graded materials to propose a new class of transversely curved metamaterial architectures with high specific stiffness for operations under extreme surrounding conditions. We envisage the next-generation concept design of hydrogen storage tanks with functionally graded metamaterial core for aerospace and automotive applications. Based on such innovative lattice metamaterial based design of hydrogen storage tanks it is possible to enhance the storage capability in terms of internal pressure and resistance to external loads and impacts. Most importantly the proposed concept would lead to a breakthrough in developing load-bearing energy storage devices. For the metamaterial core, hexagonal bending-dominated unit cell architecture with transversely curved connecting beam-like geometries would ensure the dual functionality of high specific stiffness and energy absorption capability which are mutually exclusive in traditional lattice metamaterials. The functionally graded beams, a periodic network of which constitutes the lattice, are modelled here using 3D degenerated shell elements in a finite element framework. Geometric nonlinearity using Green–Lagrange strain tensor is considered for an accurate analysis. The beam-level nonlinear deformation physics is integrated with the unit cell mechanics following a semi-analytical framework to obtain the effective in-plane and out-of-plane elastic moduli of the metamaterials. The numerical results show that the curved beam lattice metamaterials have significantly enhanced in-plane elastic properties than straight lattices along with a reduced disparity among the in-plane and out-of-plane elastic moduli.
