Institute Of Mechanics,Chinese Academy of Sciences
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深海耐压圆柱壳结构破坏尺度预测方法
No full text本发明提供一种深海耐压圆柱壳结构破坏尺度预测方法，属于服役安全评价领域，包括如下步骤：步骤1、根据应变表达式构建深海耐压圆柱壳结构的失效模式；步骤2、根据失效模型预测深海耐压圆柱壳结构的轴向破坏尺度。本发明不仅可用于深海大型钛合金耐压结构的失效模式及破坏尺度预测，还可预测模量较低的其他金属结构破坏问题
Shell-Stripping Mechanism of Red Sandstone Under Hypervelocity Impact with Aluminum Spheres
No full textTo investigate the size effect on fragmentation phenomena during hypervelocity impact, scaled experiments were conducted using a 30 mm smooth-bore ballistic range (DBR30) driven by a detonation-driven two-stage launching system. Unique stripping of sandstone target was observed, revealing that free-surface unloading waves govern peak pressure attenuation and fragmentation patterns. By establishing a shock wave attenuation model, the typical failure characteristics of different regions were distinguished, including jetting, crushing, and cracking. Parameter λ was defined to distinguish two forms of destruction, Class I (stripping-dominated) and Class II (cratering-dominated). Given the significant difference between the compressive and tensile strength of sandstone, the influence of the size effect on its failure characteristics was notable. This research also provides a valuable reference for understanding the evolution and formation mechanisms of binary asteroids.</p
Low-velocity impact response of functionally graded plates
No full textFunctionally graded materials (FGMs) are widely used in engineering due to their superior mechanical properties. However, their impact behavior is typically studied through numerical simulations or experimental methods, which are often time-consuming and resource-intensive. In this study, we investigate the impact response of a two-phase functionally graded plate by establishing the governing equations based on the Zener model and a modified Hertz contact law. Compared with prior studies relying on numerical or experimental techniques, this analytical approach offers a more efficient and cost-effective tool. This study is the first to extend the homotopy method-previously applied to homogeneous plates-to derive analytical solutions for functionally graded plates under impact. From the analytical solution, we derive explicit expressions for the maximum impact force, maximum impact depth, total contact time, total compression time, and the coefficient of restitution. These expressions enable us to analyze the influence of the functionally graded index, as well as the ratios of elastic modulus and density between the top and bottom surfaces of the plate during the impact process. The results quantitatively explain the superior performance of functionally graded plates and determine the optimal functionally graded index corresponding to the maximum coefficient of recovery
气压及流速可调的气动夹头控制器
No full text本发明公开了气压及流速可调的气动夹头控制器， 包括壳体、压力表、调压阀、控制开关组、限流阀组、总进气嘴、第一夹头进气嘴组和第二夹头进气嘴组， 壳体包括前侧板和后侧板， 压力表、调压阀和控制开关组分别嵌接于前侧板；限流阀组、总进气嘴、第一夹头进气嘴组和第二夹头进气嘴组嵌接于后侧板；调压阀包括调压阀体和调节旋钮， 调压阀体上连接有调压进气嘴和调压出气接头， 调压进气嘴与总进气嘴连接， 调压出气接头连接有压力表和限流阀组；控制开关组上连接有控制进气接头组和控制出气接头组。本发明将压力表、调压阀、控制开关组、限流阀组、总进气嘴、第一夹头进气嘴组和第二夹头进气嘴组集成于壳体， 即该壳体具备高集成度和完善的功能
用于同轴柱面爆燃驱动装置的旋转式高压电极
No full text本发明公开了用于同轴柱面爆燃驱动装置的旋转式高压电极， 包括导电芯极、绝缘套、螺纹压帽、密封压环、锁紧螺钉；导电芯极具有第一导电芯极部、第二导电芯极部和第三导电芯极部；锁紧螺钉上套接有旋转绕子， 旋转绕子位于锁紧螺钉靠近中心孔一侧， 第三导电芯极部远离第二导电芯极部一端与锁紧螺钉相连接；旋转绕子上设置有凹槽， 其中， 第一方向为第三导电芯极部指向第一导电芯极部的方向；绝缘套具有与第一导电芯极部相配合的第一包覆部、第二包覆部和第三包覆部；密封压环与爆燃驱动段之间的接触面以及密封压环与第三包覆部之间的接触面分别安装有密封圈。本发明便于安装或更换点火丝， 而且能够保证点火丝与爆燃驱动段之间精确同轴
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No full textDynamics of a spherical particle in a low-Reynolds-number fluid confined between two concentric spherical walls
No full textDynamics of a spherical particle and the suspending low-Reynolds-number fluid confined between two concentric spherical walls were studied numerically. We calculated the particle's hydrodynamic mobilities at various locations in the confined space. It was observed that the mobility is largest near the middle of confined space along the radial direction, and decays as the particle becomes closer to no-slip walls. At a certain confinement level, the maximal mobility occurs near the inner wall. We also calculated the drift velocity of the particle perpendicular to the external force. The magnitude of the drift velocity normalised by the velocity along the external force was found to depend on particle location and the confinement level; it is observed that the maximal drift velocity occurs near the wall. Fluid vortices in the confined space induced by particle motion were observed and analysed. In addition, we studied particle trajectories in the flow when the walls rotate at constant angular velocities. The externally applied force, rotation-induced flow and centrifugal/centripetal force, and particle-wall interaction lead to various modes of particle motion. This work lays the foundation to understand and manipulate particulate transport in microfluidic applications such as intracellular transport and encapsulation technologies
Convolutional-SMART: a fast reconstruction technique for tomographic PIV
No full textTomographic reconstruction, a critical process for tomographic particle image velocimetry (Tomo-PIV), remains inefficient due to the required massive memories and high computational cost. In this work, a fast tomographic reconstruction technique is proposed to improve the efficiency significantly. The weighting coefficient, which represents the contribution of the voxel to the corresponding pixel intensity, is remodeled to be independent of the voxel's positions by artificially improving the particle image resolution. Consequently, the simultaneous multiplicative algebraic reconstruction technique (SMART) is re-implemented with convolution operations. The proposed method is named Convolutional-SMART (Conv-SMART). Moreover, the numerous convolution operations are accelerated using a graphics processing unit (GPU) to further reduce the reconstruction time. A synthetic three-dimensional 3D experiment with a vortex ring is carried out to numerically evaluate the precision and efficiency of the proposed method. The results show that the speed-up ratio of Conv-SMART to the original SMART reaches about five times faster in the central processing unit (CPU) environment and 15 times faster in the GPU environment without losing accuracy when the particle density is 0.05 particles per pixel (ppp) and the resolution is 20 voxels/mm. The speed-up ratio as a function of the particle density and resolution is also provided. Conv-SMART is also applied to the left ventricular Tomo-PIV experiment. The velocity field derived from Conv-SMART is consistent with that from SMART, whereas Conv-SMART achieves 50 times faster within the GPU
An overbend strategy to manyfold enhance the designed elastic bendability of flexible electronics
No full textElastic bendability is crucial for flexible electronics to achieve conformal contact and enable widespread applications. However, reducing the thickness of the structure is almost the only strategy to enhance the elastic bendability of inorganic flexible electronics. This study proposes an overbend strategy, whose operation is beyond the designed elasticity of the fabricated structure. Mechanical theories, finite element analysis, and experiments verified that, with multilayer stacks and interconnects with various geometric designs as examples, the overbend strategy can enhance the designed elastic bendability to twice for the material of the ideal elastoplastic/kinematic hardening constitutive relationship and to more than twice for the mixed hardening/isotropic hardening constitutive relationship. The mechanism is extending the elastic strain range at the critical section to twice or more times the original value by the evolution of the elastoplastic constitutive relationship. Notably, the overbend strategy is virtually costless, combinative with other strategies and widely applicable for inorganic flexible electronics
Hot carriers and hot phonons in MAPbI<sub>3</sub> under pulsed excitation
No full textA deeper understanding of the physical properties of highly promising organic-inorganic hybrid materials, such as methylammonium lead iodide (MAPbI3), is crucial for advancing high-performance optoelectronic devices. This perspective examines the interaction between such typical materials with pulsed lasers, focusing on the dynamics of hot electrons and hot phonons. Various models describing carrier cooling are discussed, with emphasis on the role of non-equilibrium phonons and related computational approaches. The behavior of longitudinal optical (LO) phonons and the mechanisms governing lattice equilibrium remain incompletely understood. Insights from recent experiments may help develop a comprehensive model of hot carrier dynamics. By describing the dynamics of hot electrons and hot phonons, this study aims to identify methods to slow down the relaxation of hot carriers