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Application of Taguchi methodology for optimization of process parameters in laser bending of Al sheet
摘要： Laser bending process has many advantages including high flexibility, production of intricate shapes, precise incremental adjustments etc. The use of Nd:YAG laser for bending thin sheet aluminium is done frequently for various operations.In this experiment laser process parameters were optimized using Taguchi method. The response parameter governing the laser beam in Aluminium sheet bending were evaluated by measuring of the bending angle. Four input parameters such as laser power, scan speed, pulse diameter and pulse duration were taken into consideration for optimization. Furthermore, 25 combinations of these laser parameters were set and Taguchi methodology is used. The optimum parameter settings are: laser power 2.8 J, pulse diameter 2.0 mm, pulse duration 0.5 ns and scan speed 60%. The optimal result was confirmed with a superior bending angle as 200.
关键词： Bending angle,S/N ratio,Taguchi method,Spring back effect
更新于2025-09-23 15:21:01
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Analytical model for estimating bending angle in laser bending of 304 stainless steel/Q235 carbon steel laminated plate
摘要： Compared with the single-component metal plate, the stainless steel-carbon steel laminated plate (SCLP) combines the stainless steel layer and the carbon steel layer with a special preparation technique. In order to estimate the bending angle of laminated plates accurately, it is of great significance to establish an analytical model. Based on the temperature gradient mechanism, the temperature distribution equation of the SCLP is established by the piecewise function. Then, the depth of the plastic zone is calculated by the recrystallization temperature according to the temperature distribution along the thickness direction of the SCLP. Moreover, by fitting the yield strength curves of stainless steel and carbon steel, the average compressive stress of the plastic zone is calculated through the integral method. By optimizing the calculation of the plastic depth and the average compressive stress in the plastic zone, the analytical model is established based on mechanical equilibrium equations. The experimental verification shows that the average error of bending angle using the proposed model is 9.95%, while Liu’s model is 38.02%. The proposed model provides a calculation method for estimating the bending angle, which contributes to improving the accuracy of the analytical model in laser bending of SCLP.
关键词： stainless steel-carbon steel laminated plate,analytical model,bending angle,laser bending,depth of plastic zone
更新于2025-09-19 17:13:59
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Online measurement of the surface during laser forming
摘要： The laser forming process is characterized by high temperature gradients and localized deformation. The process uses a laser to introduce thermal strains. The localized deformation along with the high temperature gradients is introduced iteratively which creates a complex and dynamic forming process. To understand the dynamic behavior of the process, various models have been used. A limitation of these models is that verification is commonly based on comparison with the final shape. The present work is an attempt to measure the dynamic response during laser forming. This work will present a laser forming setup for measuring the dynamic response of a v-bend. A 2D laser range scanner was used for measuring a line perpendicular to the laser heating scan path. By scanning multiple samples and changing the relative position of the 2D laser range scanner along the laser heating scan path, a surface can be generated. Analysis of the surface shows that the plate undergoes different deformation profiles during forming—this can help in understanding the changes that incur during laser forming. A case study is performed where the experimental results are compared with a state-of-the-art numerical model with good correlation between results. This shows that the measured dynamic response can be used for improved verification of numerical models of laser forming to increase confidence in the numerical results.
关键词： Online measurements,FEM,Laser forming,AISI 304,Bending angle
更新于2025-09-16 10:30:52
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Wave-optics uncertainty propagation and regression-based bias model in GNSS radio occultation bending angle retrievals
摘要： A new reference occultation processing system (rOPS) will include a Global Navigation Satellite System (GNSS) radio occultation (RO) retrieval chain with integrated uncertainty propagation. In this paper, we focus on wave-optics bending angle (BA) retrieval in the lower troposphere and introduce (1) an empirically estimated boundary layer bias (BLB) model then employed to reduce the systematic uncertainty of excess phases and bending angles in about the lowest 2 km of the troposphere and (2) the estimation of (residual) systematic uncertainties and their propagation together with random uncertainties from excess phase to bending angle profiles. Our BLB model describes the estimated bias of the excess phase transferred from the estimated bias of the bending angle, for which the model is built, informed by analyzing refractivity fluctuation statistics shown to induce such biases. The model is derived from regression analysis using a large ensemble of Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) RO observations and concurrent European Centre for Medium-Range Weather Forecasts (ECMWF) analysis fields. It is formulated in terms of predictors and adaptive functions (powers and cross products of predictors), where we use six main predictors derived from observations: impact altitude, latitude, bending angle and its standard deviation, canonical transform (CT) amplitude, and its fluctuation index. Based on an ensemble of test days, independent of the days of data used for the regression analysis to establish the BLB model, we find the model very effective for bias reduction and capable of reducing bending angle and corresponding refractivity biases by about a factor of 5. The estimated residual systematic uncertainty, after the BLB profile subtraction, is lower bounded by the uncertainty from the (indirect) use of ECMWF analysis fields but is significantly lower than the systematic uncertainty without BLB correction. The systematic and random uncertainties are propagated from excess phase to bending angle profiles, using a perturbation approach and the wave-optical method recently introduced by Gorbunov and Kirchengast (2015), starting with estimated excess phase uncertainties. The results are encouraging and this uncertainty propagation approach combined with BLB correction enables a robust reduction and quantification of the uncertainties of excess phases and bending angles in the lower troposphere.
关键词： wave-optics uncertainty propagation,bending angle retrievals,refractivity fluctuation statistics,GNSS radio occultation,boundary layer bias model
更新于2025-09-10 09:29:36