Sandwich Panel has attracted designer’s interest due to its light weight, excellent corrosion characteristics and rapid installation capabilities. It has been implemented in many industrial application such as aerospace, marine, architectural and transportation industry. Its structure consists of two face sheets and core. The core is usually made of material softer than the face sheets. The current investigation unveils the effect of core thickness on the behavior of Sandwich Panel beyond the yield limit of core material. The core thickness is investigated by utilizing univariate search optimization technique. The load is applied in quasi–static manner (in steps) till face sheets reach the yield limit. Simply supported panel from all sides is modeled using a finite element analysis package. The model is validated against numerical and experimental cases that are available in the literature. In addition, experimental investigation has been carried out to validate the finite element model and to verify some selected cases. The finite element results show very good agreement with the previous work and the experimental investigation. The study presents that the load carrying capacity of the panel increases as the core material goes beyond the yield point. Also, increasing core thickness to a certain limit delays the occurrence of core yielding and gives opportunity to face sheets to yield first.
We present a numerical study for the suppression of self-excited vibrations represented by a Rayleigh oscillator using an impact viscous damper. A systematic approach based on a univariate search optimization method is used to determine the best design parameters for suppressing self-excited vibrations. The suggested system is found to be effective in suppressing this type of vibration. Optimum parameters for complete quenching of such vibrations are obtained. We investigate quasi-static as well as dynamic variations of the bifurcation parameter for both supercritical and subcritical Hopf bifurcation.
Baseline data is produced for designing an optimum Defense Hole System (DHS) for a large plate with a circular hole in shear dominant-load range. Stress concentration associated with circular holes for tensile/shear ratio ranging from 0% to 25% is reduced by 13.5% to 16.67%, respectively. This reduction is achieved by introducing auxiliary elliptical holes (i.e., DHS) along the principal stress directions. Each pair lies along the same principal direction has the same geometry and placement on either side of the main hole. These holes are placed in the low stress regions. With such reduction in the maximum stress level, the improvement in fatigue life of a structural part can be very significant. Both redesign optimization and parametric optimization techniques are utilized to reach the optimum solutions and to generate the baseline data. Finite Element Analysis (FEA) is used to evaluate the stresses and to optimize the size and location of the DHS. The optimum cases are validated using the RGB-photoelasticity technique. Three main goals are achieved by introducing such holes: maximum stress reduction, working as crack arrest in case a crack propagates, and material reduction.
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