Optimal Design of Large Circular Vibrating Screen Based on MultipleFrequencies Constraints and Analytical Sensitivity Methods
Multiple frequencies constraints and analytical sensitivity methods were used in structural optimization design of the side plate of 4YK1860 vibrating screen to lower the damage of side plate caused by high dynamic stress. The mass of side plate of the vibrating screen was taken as object function, mode frequencies were regarded as state parameters, size of plate were used as constraint parameters and an optimization criterion which is applicable to solve this kind of problem was given. Meanwhile, sensitivity characteristics of variable parameters were considered during the process of optimization. The results show that the optimization program with embedded analytical sensitivity calculation methods is of a higher solving precision and with a more stable calculating process. After structure optimization, the thickness of side plate to withstand large impact is increased, the thickness of stiffener and peripheral angle are decreased, the mass of side plate is reduced by 7.75% and a better optimization effect is achieved. The analysis of the optimal vibrating screen presents that the mass of vibrating screen decreases by 3.5%, elastic deformation frequency which is close to the working frequency increases by 8.8% and the dynamic stress decreases by 48%. The natural frequencies of vibrating screen are improved and modal frequency is far from the working frequency of the exciting motor, stress concentration of vibrating screen is weakened and thus the structural stiffness and reliability of vibrating screen is enhanced.
Optimization of structures with multiple frequency constraints
Abstract The problem of designing a structure with multiple frequency constraints by using an optimality criterion method was investigated. The frequency constraints include the condition that the frequencies are equal or separated by a specified interval with a preselected vibration mode associated with the fundamental frequency. Three different scaling procedures are discussed to make the fundamental or any other frequency equal to the desired value. A 38 member truss structure with different constraint conditions and two distributions of nonstructural masses was optimized.
Evaluation of buckling load and dynamic performance of steel shear wall retrofitted with strips made of shape memory alloy
One of the most imperfections of the steel shear wall is out of plane displacements that cause severe damage in both structural and non-structural elements. In this paper, the effects of shape-memory alloys on steel shear walls are investigated. First, a numerical analysis using the finite element method in ABAQUS software has been carried out according to an experimental test. The results of the numerical analysis have been verified with experimental results. Next, shape-memory alloy fibers have been added vertically and horizontally to various parts of the steel shear wall. The results show that retrofitting with the shape-memory alloy reduces the out-of-plane displacement of the steel shear wall under both cyclic and seismic loadings. Besides, the buckling load in the steel shear wall increases when it is retrofitted with the shape-memory alloy. Also, the total out-of-plane movement (accumulated absolute displacements) of the steel shear wall and non-structural damage are controlled by the characteristic of a shape-memory alloy material called “super-elastic”.