Papers by Keyword: Energy Dissipation

Abstract: Full face rock tunnel boring machine in construction process, disc cutter put pressure on rock breaking, actually belongs to the process of energy transfer, from the point of view of energy analysis the energy transfer rules in the process of disc cutter rock breaking, based on CSM force prediction model, analysis disc cutter energy input and rock mass energy output efficiency ratio, for excavation with minimum energy efficiency. Taking S-536 Hong Kong water tunnel TBM as an example, When the penetration is 10mm, based on the energy efficiency ratio the optimal disc cutter spacing should be less than 70mm, than the actual average disc cutter spacing is small 2mm, rock mass as a reference the disc cutter rock breaking efficiency mechanism provides certain reference value for the cutter layout.

Abstract: A new type of shock absorber was designed. The shape memory alloy (SMA) bars were used as the kernel components for energy dissipation and restoration in the stress mode of pure tension. Their initial deformation was enlarged by the hydraulic system with two pistons of different sizes. In this way, high material utilization and high relative displacement were guaranteed together. The prototype device was fabricated, analyzed and experimental tested. The results show that the shape and amplitude of the force-displacement curve of the device could be easily changed by varying the hydraulic system, the number and/or the characteristics of the SMA bars. The new device can be separately or combined used as shock absorber and/or vibration isolation component for vehicles or other machines.

Abstract: This research investigated the influence of mortise-tenon joint before and after damage on seismic performance of ancient lifted-beam timber structure. Dynamic responses of an ancient timber structure under various earthquake intensities were analyzed by ANSYS to extract the M-θ hysteresis loops of mortise-tenon joints before and after damage. The area of the largest hysteresis loop was taken as quantitative indicator to measure energy dissipation of mortise-tenon joints. The results shows that if some mortise-tenon joints were damaged, they dissipated much less earthquake energy decreasing by 31.8%-38.5%, and top displacement of structures increased by 1.79%-5.96% correspondingly. Moreover, the displacement under 8-degree-fortification, 7-degree-rare earthquake intensity increased most obviously. Therefore, energy dissipation of mortise-tenon joint is a main indicator to the assessment of seismic performance of a damaged ancient timber structure.

Abstract: The steel frame with wedge devices is a kind of shock structure based on the node energy consumption. The seismic performances of steel frame with wedge and ordinary steel frame model under low cycle reciprocating load simulation analysis and time history analysis under earthquake loads are analyzed by using finite element software, compared the respective energy dissipation performance and seismic performance, the results show that the wedge spring damping device can effectively control story drifts of structure, reduce the seismic response of structure, and well consume the seismic energy, so the structure of the new column bases with wedge spring devices show better seismic performance.

Abstract: Buckling Restrained Brace, Abbreviated as BRB in thefollowing content, a new omponent dissipating energy and absorbing quake ,as itis installed steel constrained unit to prevent overall instability ,it can notonly maintain its stiffness and stability, but also dissipate seismic energy bythe steel core material, as a result we can protect the main structure of thebuilding. This paper focuses on the buckling restrained braced frame (BRBF) ofthe energy principle、calculation method and thespecific design process.

Abstract: Belt and airbag are the most important protection devices in vehicle frontal crash, which can have the best protective performance when only they were well matched with vehicle body structure. In this paper the theoretical guidance for optimizing belt and airbag parameters is researched, in order to improve the effect and efficiency of parameters optimization of restraint system. Firstly, a simulation model for occupant restraint system is developed based on the finite element theory combined with multi rigid body theory, and its effectiveness for simulating the occupant dynamic response in frontal impact is validated. Then, the energy dissipation characteristics of occupant head and chest in typical frontal crash are analyzed based on the developed model. Lastly, the adaptive level of restraint system parameters are evaluated according to the dissipation characteristics of occupant energy, and theoretical guidance for parameters optimization are summarized based on the evaluation. The analysis results indicate that: (1) airbag with low stiffness cannot fully utilize the deformation of vehicle body to dissipate the energy of occupant head, but may increase the risk of head injury; (2) belt with high stiffness would apply a big force to occupant, which could increase the compression amount of chest and may increase the risk of chest injury.

Abstract: The security researches of energy dissipation were always the focus in the High arch dams. Statistically, the trajectory type energy dissipation is the most widely used in the built high arch dams, and the protected plunge poor were always set downstream the dam body. However, the widely used protected plunge poor need large investment with the disadvantage of complicated operation and maintenance. Along with the construction of concrete high arch dam in the Southwest China, the “Reventment-Protected and Non-Bottom-Protected Plunge Pool” has been studied and proposed, which has the advantage of more simplified project design and more economy investment.

Abstract: In recent years, fatigue limit estimation based on dissipated energy has been introduced in various industries because of its time and cost effectiveness. However, the mechanism of energy dissipation and the relationship between energy dissipation and fatigue damage have not been investigated well. In this study, mechanism of energy dissipation is investigated in relation with formulation of slip bands for JIS type 316L stainless steel through observation of slip bands by optical microscope and atomic force microscope.

Abstract: We applied the discrete element method (DEM) to analyze the normal impact properties of elastoplastic spherical particles. DEM simulation of impact between two identical elastoplastic spheres is carried out to validate the proposed model. The numerical results show well agreement with the FEM solution. Based on this model, the effects of impact parameters such as velocity, yield strength, elastic modulus, Poissons ratio, and mass density, on the loss factor in impact process, are then analyzed.

Abstract: This paper introduces a variety of viscous damper installation form, including brace, herringbone and cantilever wall installation. By an example, install the bracing form, herringbone installation form and type cantilever wall installation condition are compared, And to calculate the results of its damping effect has carried on the comparative study, The superiority of the cantilever wall type layout pattern is obtained.