Iskanje po katalogu digitalne knjižnice

Opis: Determining the in-situ engineering parameters of sandy soils has always been a challenge for geotechnical engineers, resulting in several methods having been developed so far. The Perth Sand Penetrometer (PSP) test is one of the most versatile of these methods. It is a considerably faster and cheaper tool than boring equipment, especially when the depth of the exploration is moderate. In the present research, a methodology for the use of a PSP device to evaluate the engineering parameters of sandy soils in laboratory conditions is discussed and the repeatability of the test results is studied. First of all, the tests were performed on typical Tehran young alluvial deposits (poorly graded sandy soil, SP) consistently prepared to 5 densities using the sand raining or pluviation technique. Next, the normal and logNormal distributions of the test data using the Kolmogorov-Smirnov normality test were examined. After that, based on the obtained results, the relationship types between the dynamic point resistance index (qd) and other parameters, such as the relative density (Dr), the modulus of elasticity (E), the shear modulus (G) and the friction angle of the soil, were determined. The results show that the obtained relationships were semi-logarithmic and logarithmic, and most of the obtained experimental formulas had a high coefficient of determination (>90%). To evaluate the accuracy of the results, 95% confidence and prediction bands were also used and the results show that all the obtained experimental relationships were appropriate. Finally, the repeatability of the test results was evaluated by calculating the coefficient of variations, which was less than 30% for all the tests.
Ključne besede: dynamic-point resistance index (qd), engineering parameters, repeatability, statistical methods
Objavljeno v DKUM: 18.06.2018; Ogledov: 1118; Prenosov: 224
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Opis: Purpose of this paper is to present basic solutions on shape complexity, based on basic information of the STL data. Design/methodology/approach: Paper presents a few methods of mathematically evaluating the complexity of the shape. Methods vary from very simple based on the number of triangles in STL file, STL file size and the parts volume, to the more complex mathematical evaluation based on the basic relations of the STL data. Findings: We discovered that evaluation of shape complexity based only on basic data of STL data gives us some basic results on part complexity and can be used for further researches. Research limitations/implications: For parts with large block volume/part volume ratio and thinner parts with free form surfaces only the first method is suitable and gives suitable results. Practical implications: In a rapidly developing field of manufacturing technologies choosing the optimal manufacturing procedure is a difficult and crucial decision. Usually the decision is based on experience evaluation that is fast and can be optimal. Usually, this method produces goods results, but in some cases this method can lead to cost increases and reduced economic efficiency without us even knowing that. Therefore, it is crucial, that a fast and simple solution is developed, by which the optimal way of manufacturing can be determined. Originality/value: Choosing maximum efficient manufacturing processes on base of part complexity is a new perspective in manufacturing, which, properly evolved and complied can cause revolution in manufacturing optimization, especially in hybrid manufacturing processes.
Ključne besede: manufacturing systems, shape complexity, complex shapes, manufacturing optimization, engineering design, STL files, STL file parameters
Objavljeno v DKUM: 01.06.2012; Ogledov: 2098; Prenosov: 68
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