Energy Dissipation Characteristic of Red Sandstone in the Dynamic Brazilian Disc Test with SHPB Setup

In order to quantitatively investigate the energy dissipation characteristic during the dynamic tension failure of rock materials, the dynamic Brazilian disc tests on red sandstone were conducted using the split Hopkinson pressure bar (SHPB) setup. The states of the specimens after different incident energies can be divided into three forms (i.e., the unruptured state, the ruptured state, and the broken state), and the failure processes of the specimens were recorded by using a high-speed camera. The results show that the ruptured state of the specimen corresponds to the critical failure strain. Taking the critical incident energy as a turning point, two positive linear fitting relations between the dissipated energy and incident energy before and after the point are obtained, and the dynamic linear dissipation law is found. When the incident energy is less than the critical energy, specimens were unruptured after impact. When the incident energy is greater than the critical energy, specimens will be broken after impact. According to the obtained linear energy dissipation law, the dynamic tensile energy dissipation coefficient (DTEDC) was introduced for quantitatively describing the dynamic energy dissipation capacity of rock materials in the dynamic Brazilian disc test. When the specimen is in the unruptured state, the ideal DTEDC is a constant value. When the specimen is in a broken state, the DTEDC increases with the increase of incident energy.

Coupled Static-Dynamic Tensile Mechanical Properties and Energy Dissipation Characteristic of Limestone Specimen in SHPB Tests

To investigate the dynamic splitting tensile mechanical property of limestone under coupled static and dynamic state, the dynamic split tensile tests of limestone under one-dimensional coupled static and dynamic load with different strain rates were performed with the help of modified split Hopkinson pressure bar (SHPB) equipment. The dynamic splitting tensile mechanical property and energy dissipation characteristic under two stress states were also compared in this research. Test results indicated that the dynamic tensile strength of the limestone specimen increased with the increase of average strain rate, exhibiting an obvious strain rate effect. In addition, dynamic tensile strength under uniaxial state was higher than that under one-dimensional coupled static and dynamic load state under the same test condition. Moreover, the deformation modulus increased with increasing average strain rate under uniaxial state, while it decreased with increasing average strain rate under coupled static and dynamic state. Both the reflected energy and absorbed energy linearly increased with increasing incident energy. The preload in the radial direction could increase the reflected energy and decrease the absorbed energy. Moreover, the transmitted energy with preload state was slightly lower than that under uniaxial state. Finally, the dynamic tensile strength of limestone specimen increased as a power function with increasing absorbed energy.

Experimental investigation of the dissipation characteristic of sandwich structures with periodically perforated viscoelastic damping material core

Wave energy can be dissipated gradually when it is propagated in viscoelastic damping material (VDM) composite structures. In this paper, after the specimens with different opening ratios (ORs) of VDM layer are prepared, the elastic wave energy propagation and dissipation characteristic of periodically perforated VDM cored sandwich structures are investigated by an experimental method. The sandwich structures are discretized into several testing points in our experiment. When the complex velocity, equivalent effective mass, and external excitation forces have been obtained at each testing point by sensors, the energy dissipation in the sandwich structure is determined based on the energy dissipation mechanism of wave transmission in solid. The experimental results are then compared with theoretical and numerical simulation results. By analyzing the computational accuracy of theoretical and numerical results using experimental data, it is shown that high consistency between theoretical, numerical, and experimental results can be achieved, especially in the medium-frequency and high-frequency ranges. Thus, our experimental results demonstrate that periodically perforated VDM sandwich structures can be applied to engineering practice for their good performance of dissipation characteristics in the middle-frequency and high-frequency ranges.

Design and Implementation of Measurement System for Power Dissipation Characteristic of Vibration Damper Based on Virtual Instrument

In order to overcome the disadvantages of traditional instrument for performance test of vibration damper, a power dissipation characteristic measurement system based on virtual instrument was developed. A fully digital test platform was constructed through the use of modular and networked data acquisition equipment. Real-time display and automatic analysis of various measuring parameters were realized. The system has higher efficiency than traditional instrument. Moreover, it is easy to expand base on this existing modular system for further testing requirement.