Applied Mechanics and Materials Vols. 117-119

Abstract: In order to reduce the longitudinal displacement of longitudinal floating bridge subject to earthquake excitation, seismic response reduction control strategy for longitudinal floating bridge with MR damper is developed based on the MATLAB software for numerical simulation and the vibration control algorithm of classical linear quadratic of full-state feedback. In this paper, the seismic response reduction analysis for a longitudinal floating bridge, Pingsheng Bridge which is a self-anchored suspension bridge with a single tower, is completed, and also the optimal active control force is obtained. Furthermore, the effect of time delay on seismic control is investigated. The results show that the longitudinal displacement of longitudinal floating bridge can be effectively reduced by vibration control system with MR damper, and the time delay has little influence on seismic response reduction of longitudinal floating bridge.

Abstract: On conditions of different weight and height, the tunnel portal structure’s accelerations evoked by rock-fall impaction have been researched in laboratory by using a 1/30 scale similar model. The study shows that the normal acceleration value is the biggest, the lateral acceleration is second and the longitudinal acceleration is the minimum. There is a simple linear relationship between the structure’s acceleration, the rock weight and the rockfall height when the slope gradient is 1:0.5 and the slope surface is slippery. The multiple linear relationship between the structure’s normal acceleration, the rock weight and the rockfall height has been obtained.

Abstract: Abstract. This paper introduces an architecture design of airborne equipment integrated mounting shelf, including constitution of mounting shelf, design method, vibration isolation design,finite element analysis and calculation, etc. Mounting interface between mounting shelf and airborne aircraft is complicated; weight is limited; load on mounting shelf is big and mechanically severe environment must be met. Through dedicated design and simulation analysis, this product has passed each item of airborne environment tests and equipped in military.

Abstract: The ingot of Ti47Al alloy was prepared by a newly developed rapid directional solidification, the microstructure and compressive properties of the ingot was observed and tested. The results show that the macrostructure consisted mainly of coarse columnar grains parallel to the axial direction, with the size of 0.5mm wide and 10mm in length. The direction of lamellar is almost perpendicular to the growth direction in the longitudinal section and no dendritic core is found. The average ultimate compressive strength of the specimens with grain growth parallel/perpendicular to the compressive direction is 1233.3 and 861.7 MPa respectively. The fracture mode for specimens with grain growth parallel to the compressive direction exhibits predominantly translamellar fracture, however, that for specimens with grain growth perpendicular to the compressive direction exhibits predominantly delamenation or interlamellar fracture.

Abstract: A vibration calculation model for a large-scale hydraulic turbine group is built to act on the unbalanced force between the rotor and the runner. Take the Francis turbine group for example. Using the finite element method, the units lateral vibration characteristics of rotating components were calculated and analyzed. The paper discusses the impact of location and the guide bearing stiffness on the lateral vibration characteristics of the unit. Based on the elastic supporting models, the paper also compares the results of the guide bearing stiffness modified simultaneously and respectively. Results show that the guide bearing stiffness has a significant impact on the lateral vibration characteristics of the location of the unit, which provides a reference for the reduction of vibration and the optimization of the supporting structure of the turbine unit.

Abstract: The estimation of dynamic responses of a bridge under vehicle loads moving along the bridge is frequently a problem of great interest for bridge engineers. Presented herein is an analytical approach to estimate the dynamic responses of a simply supported Euler-Bernoulli bridge under a set of vehicle axle loads moving along the bridge at constant speed. The approach involves convolution of the vehicle axle loads with modal responses of the bridge. The convolution integral is solved in time domain by a numerical integral approach. The solution was verified and good agreement was found.

Abstract: Send laser cladding experiments to the substrate surface in 16Mn in the Synchronous way. By different laser cladding parameters on the microstructure and mechanical properties under the comparative analysis, to make a more detailed discussion of laser cladding power and scanning speed on the quality of laser cladding. Different process parameters on the microstructure of cladding layer and the cladding layer of particle distribution and the tissue distribution of species .We get to the study that type and distribution of the cladding layer microstructure and tissue distribution of tungsten carbide hard phase. We get regular pattern that technological parameter has an effect on the quality of cladding layer. We can came to the conclusion that the best cladding process parameters is in the power of 3.0KW and cladding speed 1000mm/min.

Abstract: In this paper we conduct study on flow-induced vibration of large-span upwelling radial steel Gate and its hydraulic hoist. Place an emphasis on vibration response characteristics under two working conditions of diversion and drainage, which proves the safety of hydraulic hoist gate vibration caused by gate vibration. Firstly, we study on dynamic characteristics of fluid-structure interaction of association system of gate and start and stop lever, reveals the discipline of the effect fluid having on structural dynamic characteristics. On this basis, flow-induced vibration characteristics under two conditions of with and without start and stop lever action considered. The results indicate that the gate vibration response with hydraulic hoist used decreases, which explains start and stop lever has certain effect of restraining vibration on gate vibration. In addition, under the working condition of drainage the vibration magnitude of start and stop lever is smaller than that of gate body, which explains there is damping action during transference of gate vibration through start and stop lever. The results find out that on the assumption of optimized gate structure and hydraulic arrangement, it is practicable, safe and reliable to adopt hydraulic hoist. The achievement has directive significance on similar projects construction in the future

Abstract: A theoretical analytical solution on the linear responses of axially loaded beams subjected to arbitrary transverse impulsive loads was proposed in this paper, based on the Timoshenko’s beam theory. The equivalent matrix of frequency, matrix of loads and modified matrix of mass were established respectively. Furthermore, the affecting parameters of the beams such as length-depth ratio, axial compression ratio, boundary constraints and load conditions were discussed based on the analytical solution developed above, which were assumed subjected to the typical triangle impulsive loads. The results and conclusions were also helpful to the anti-blast analysis of columns

Abstract: Hairspring is a fine spiral spring, which is the key component in mechanical watch movement for timekeeping. According to literatures, there are only few studies on hairsprings or spiral springs. Using the Castiliago’s method, the mechanics of hairspring is studied in details. And Computer simulation with Matlab® and experimental validation are also conducted to show the spring frequency. Experiment shows that the theoretical analysis and computer simulation can be used to guide and facilitate the design of hairspring or spiral spring.