Papers by Author: Yu Hua Lin

Abstract: This paper presents a inverse method to derive the material properties from the resonance frequencies of a free-edge test specimen based on modal vibration test. A mixed numerical experimental identification procedure is used for this purpose. Finite element models of the test plate is simultaneously updating and reproduces the updating frequencies, then optimal procedure is running. The sum of the squared differences between the experimental and the finite element method numerical resonance frquencies is the objective function. To seek practical solutions, here presents a global optimization method--simulated annealing method for the determination of the elastic properties. The inverse method is applied to determine the elastic constants of aluminum , carbon/epoxy , Glass/PP composite material and double coated steel plate. The results indicate that the method can obtain very accurate elastic constants for aluminum , Glass/PP , carbon/epoxy composite material ,but for double coated steel plate , if the individual layer of the three different layers is as isotroptic material having six elastic constants , the method can obtain very accurate results , but if it is as transversely isotropic material having twelve elastic constants, the evaluating elastic constants are bad.

Abstract: This paper presents an inverse method to derive the elastic constants of thick composite plates from the resonance frequencies of a free-edge test specimen based on modal vibration test. A mixed numerical experimental identification procedure is used for this purpose. The sum of the squared differences between the experimental frequencies and analytical frequencies from finite element method is chosen as the objective function. The optimization techniques, Hybrid Genetic /Simulated Annealing algorithm, have been applied to determine the elastic constants. As the objective function reaches its minimum, its corresponding design variables are the elastic constants of the material. The present method is applied to determine the elastic constants of AS4/PEKK material. The results indicate that different stacking sequences and numbers of frequencies have effects on the determination of elastic constants of the materials.

Abstract: This paper proposes an inverse method to obtain the elastic properties of material. The sum of the squared differences between the experimental resonance frequencies and calculated resonance frequencies from the finite element method is chosen as the objective function. The proposed method presents an optimization method, Hybrid Genetic /Simulated Annealing algorithm, to determine the elastic properties. When the objective function reaches its minimum value, its corresponding design variables are the elastic constants of the material. The inverse method is applied to determine the elastic constants of aluminum plate, Glass/PP laminate, and double coated steel plate .The results indicate that for few elastic constants as an aluminum plate, Hybrid Genetic /Simulated Annealing algorithm has no apparent improvement, but more calculation time in comparison method. While simulated annealing while for Glass/PP laminate and double coated steel plate with more elastic constants, Hybrid Genetic /Simulated Annealing algorithm is superior to the traditional simulated annealing method.

Abstract: This research utilizes an image-vision-system to measure the size of the product-burr. The relational expression was established between the clearance of micro punching die and burr size after blanking the composite material via a neural network. This can help to anticipate the burr size under any clearance and used cycles of punching die. The purposes of this research are: (1) it can predict the used cycles of punching die at any clearance between the punch and die, the engineer can change the punching dies at right moment to prevent the bad product from producing; (2) it can utilize this research to find out the optimum clearance condition which can avoid bad design of the punching die, which will take long time to repaired the punching die.