Overpressure

About: Overpressure is a research topic. Over the lifetime, 3236 publications have been published within this topic receiving 34648 citations.

Forecast of Airblast Vibrations Induced by Blasting Using Support Vector Regression Optimized by the Grasshopper Optimization (SVR-GO) Technique

Abstract: Air overpressure (AOp) is an undesirable environmental effect of blasting. To date, a variety of empirical equations have been developed to forecast this phenomenon and prevent its negative impacts with accuracy. However, the accuracy of these methods is not sufficient. In addition, they are resource-consuming. This study employed support vector regression (SVR) optimized with the grasshopper optimizer (GO) algorithm to forecast AOp resulting from blasting. Additionally, a novel input selection technique, the Boruta algorithm (BFS), was applied. A new algorithm, the SVR-GA-BFS7, was developed by combining the models mentioned above. The findings showed that the SVR-GO-BFS7 model was the best technique (R2 = 0.983, RMSE = 1.332). The superiority of this model means that using the seven most important inputs was enough to forecast the AOp in the present investigation. Furthermore, the performance of SVR-GO-BFS7 was compared with various machine learning techniques, and the model outperformed the base models. The GO was compared with some other optimization techniques, and the superiority of this algorithm over the others was confirmed. Therefore, the suggested method presents a framework for accurate AOp prediction that supports the resource-saving forecasting methods.

Response of Horizontally Oriented Buried Cylinders to Static and Dynamic Loading

Abstract: : This was an experimental investigation into the response of small, shallow-buried (in dense, dry sand and stiff clay), aluminum cylinders to static (15-min rise time), rapid (13 msec), and dynamic (0.3 msec) plane-wave loading up to 500 psi. The cylinders had identical outside diameters of 3.5 in. and two thicknesses, 0.022 and 0.065 in. Hence, the cylinder stiffnesses, EI/CuR, were 1.7 and 45 (d/t = 159 and 54), respectively. In stiff clay, the overpressure required to cause collapse increased very slowly with increasing depth of burial from zero to the deepest burial, three-quarters of the diameter. The hydrostatic buckling equation, Pcr = 3 EI/CuR, was applicable for the cylinders tested. In the dense sand, the overpressure required to cause collapse increased greatly with increasing depth of burial from zero to one-eighth of the diameter. Below this depth it was not possible to collapse even the most flexible cylinders under the available 500-psi pressure. The hoop compression theory was verified. A ductility factor of about 7 was found to be conservative for cylinders buried at depths greater than one-eighth their diameter in the dense sand. The recorded strains were nonelastic in amny cases and it was shown that large yielding does not necessarily define collapse. Stress and moment were found to be nonlinear functions of overpressure, whereas thrust was generally found to be a linear function of overpressure. The differences between static and rapid loading in the elastic response of the cylinder were found to be small.

Statistical model of sonic boom structural damage

Abstract: The probabilities of structural damage from sonic booms were estimated for various susceptible structural elements using a statistical modeling technique. The breakage probabilities were found to vary widely with the specific material configuration, but to consistently increase with increasing nominal overpressures. The ranges of breakage probabilities at a nominal overpressure of 1 psf for typical configurations of susceptible materials were as follows: windows--.000004 to .00000003, plaster--.0003 to .0000005, bric-a-brac--.000001 to .00000001, brick walls--.0000006 to .000000001. The results of the modeling tend to agree well with sonic boom claims experience.

Statistical Prediction Model for Glass Breakage from Nominal Sonic Boom Loads.

Abstract: : A statistical model was developed which can be used to estimate the probability of glass breakage from sonic booms as a function of their nominal overpressure. Other parameters which can be taken into account in breakage probability calculations with this model include window size, aircraft vector, boom duration, and whether the glass was previously in good condition or cracked. A model window population has been devised from available data which includes the distributions of dynamic amplification factors and breaking pressures for seven window types. Provision has been made in the model to treat .61% of the window population as cracked glass. From computer generation of histograms from test data, the distribution of both sonic boom stresses and glass strengths were found to be lognormal. By use of the model, it was estimated that there would be 1.1 breaks per million panes in good condition boomed at a nominal overpressure of 1 psf. This estimate agrees well with sonic boom claims data. (Author)