Papers by Keyword: Stress Wave

Abstract: In recent years, there has been a tremendous increase in the use of adhesively bonded joints for the structural components as they offer various advantages such as low structural weight, low fabrication cost, and improved damage tolerance. One of the major concerns in their use is the crack produced at the interface of adhesive and adherend surface causing the failure of the joint. A study on the determination of crack growth can contribute momentously to avoid the joint failure. In this study the crack growth caused in adhesive due to displacement controlled loading has been analyzed by ABAQUS/Explicit software. Crack growth was modeled in the double cantilever beam (DCB) using traction separation law by element-based cohesive behavior. The analysis showed that: (1) The adhesive joint behaves linearly before the first cohesive element failure and after that the failure continues to increase even on decreasing the load untill it fails completely, (2) The noise during the failure of adhesive is caused due to the stress wave which is produced as a result of sudden loss in traction between the adhesive and the adherend.

Abstract: The effect of stress wave propagation on dynamic response of square tube was investigated by the experimental and numerical simulation methods in the present paper. The square tubes were subjected to the axial impact by split Hopkinson pressure bar. And the deformation process of each square tube was recorded by a high speed camera. Typical dynamic plastic buckling phenomena were observed in the experiments. And the numerical calculation of the experimental load case was conducted to analyze the effect of the stress wave propagation on the initial buckling of the square tube. The results show that there is obvious stress wave propagation in the square tube before the buckling of the square tube. And the initial buckling starts from the rear end of the tube due to the propagation of the stress wave. The relation between the stress wave propagation and initial buckling of the square tube was also discussed.

Abstract: Dynamic buckling of bars under step load was studied by considering the stress wave effect. Straight bars without axial inertia were taken as an example when deformation was small. The buckling solution satisfying the boundary conditions was given by the semi-analytic method. The buckling solution was substituted to the dynamic buckling governing equations. The unified expression of dynamic buckling critical load was obtained by discussing the character of the solution. The dynamic buckling critical load was obtained by calculating the value of when the stress wave propagated to the critical length . The value of dynamic buckling load was 2.5 times the one’s of static buckling load with corresponding equivalent length.

Abstract: This paper presents some recent developments of the Distinct Lattice Spring Model (DLSM) on dynamic fracturing of rock. The DLSM is a micromechanics based discrete numerical model for rock dynamics problems. It provides an alternative tool for rock mechanics study. Compared with the classical Discrete Element Model (DEM), the DLSM can directly use macroscopic parameters without any requirement for calibration process. Another significant advantage is that the DLSM uses only half of the degree of freedoms, and therefore, is more computational efficient. Because of these advantages, it has been used in a number of fields, e.g., dynamic fracturing, wave propagation, and nuclear waste disposition. In this work, the basic principles of the DLSM and its latest developments will be outlined.

Abstract: In order to impede stress wave propagation in mechanical boom system, this paper study on contact interface rough effect on stress wave propagation. The model of stress wave propagation was established. On stress wave test platform, it was tested that stress wave through the contact interface roughness between two contact interface. The results show that small surface rough is benefit for stress wave through contact interface; with the surface rough increase, stress wave through contact interface reduce.

Abstract: The initial buckling displacements are taken as initial conditions to solve the dynamic postbuckling problem. Non-dimensional dynamic postbuckling equilibrium equations denoted by the displacements are derived and solved by use of the finite difference method. The results reveal the regulation that the dynamic postbuckling deformation develops from the initial low step mode to the subsequent higher step modes under elastic compression wave.

Abstract: Impact coal cutting is a new kind of coal cutting method, totally different from conventional coal cutting in mechanism. To increase the blocky coal in long-wall coal face with low energy consumption, impact coal cutting is a good way to go. In this paper, an analysis of energy dissipation in impact coal cutting using stress wave is carried out. Firstly, the production, transmission and dissipation of energy are analyzed during the process of coal impact cutting, and the energy distribution area is also obtained. Secondly, the transmission rule of stress and energy are studied by the method of stress wave; through measuring the amplitude attenuation quantity of the first and any other cycle in oscillograph, the attenuation radio can be worked out. Lastly, the propagation process of energy was analyzed based on the impacting rule and propagation rule of energy; the relation between impacting consumption of energy and minimal irreversibly lost energy is expounded. It is pointed out that if the coal block is destroyed, the impacting consumption of energy must be more than the minimal irreversibly lost energy.

Abstract: In this paper the NHDMOC method which succeeded in studying stress wave propagation with one dimensional strain was applied to study the one-dimensional stress wave propagation. In this paper, the ZWT nonlinear visco-elastic constitutive relationship with 7 parameters to NHDMOC, and corresponding equations were deduced The equations was verified from the comparison of elastic stress wave propagation in SHPB with elastic bar and visco-elastic bar respectively. Finally the dispersion and attenuation of stress wave in SHPB with visco-elastic bar was studied.

Abstract: We obtain response regularity of stress wave in bolt, which regularity can be applied in nondestructive testing of anchoring quality, with establishing longitudinal one-dimensional bolt wave equation, studying longitudinal vibration responses under several boundary conditions by the principle theory of elastokinetics. And it is the principal theory that anchoring quality is deduced by bolt vibration response which is caused by dynamic transient vibration.

Abstract: This paper analyzes the propagation characteristics of stress wave in the cap-pile system. Based on reflected wave method, the propagation velocity-time curve of stress wave in the defective pile with cap is calculated theoretically. Then the calculation result shows that the waveform curve by theoretical analysis is consistent with the defect location and pile position, and the waveform curve well reflects the propagation characteristics of waves in the pipe with cap. Finally the theoretical analysis method is used to assist the field testing, and compared with the test result to describe the integrity status of pile.