There were for a long time two invariant forms of hydrodynamic equations： one was related to coordinate system of references, and the other was versus to measure units of characteristics. These both invariant forms h...There were for a long time two invariant forms of hydrodynamic equations： one was related to coordinate system of references, and the other was versus to measure units of characteristics. These both invariant forms had important roles in the development of theoretical and practical applications of hydro-aerodynamics and related industries. The third invariant form of hydrodynamic equations is one for the dimensions of spaces. For this goal, the hyper quantities （space and physics） are introduced. Then these are created we can easily cover all problems in arbitrary dimensions （3D, 2D, 1D, separate space for liquids or constituent matters）. In particularly, when they are applied to water hammer problem, which is an especially problem, we can receive immediately celerity and pressure of the event.展开更多
An effective and simple way to develop equations from impact strain signals was proposed.Little research has been performed in this area,but this equation is very important for evaluating input signals in finite eleme...An effective and simple way to develop equations from impact strain signals was proposed.Little research has been performed in this area,but this equation is very important for evaluating input signals in finite element analysis impact tests and for obtaining additional information on material deformation and fracture processes under impact loading.For this purpose,dynamic impact responses were examined through signals obtained from a strain gauge installed on an impact striker connected to a data acquisition system.Aluminium 6061-T6 was used to extract strain responses on the striker during Charpy impact testing.Statistical analysis was performed using the I-kaz method,and curve fitting equations based on the equation for vibration response under a non-periodic force were used to evaluate the Charpy impact signals.The I-kaz coefficients and curve fitting equations were then compared and discussed with related parameters,such as velocities and thicknesses.Velocity and thickness were found to be related to the strain signal patterns,curve fitting equations and I-kaz coefficients.The equations developed using this method had R2 values greater than 97.7%.Finally,the constructed equations were determined to be suitable for evaluating Charpy impact strain signal patterns and obtaining additional information on fracture processes under impact loading.展开更多
There are various methods for analyzing pile driving process such as dynamic formulas, wave equation analyses and dynamic measurements. The programs of the two latter methods are relatively expensive to purchase and a...There are various methods for analyzing pile driving process such as dynamic formulas, wave equation analyses and dynamic measurements. The programs of the two latter methods are relatively expensive to purchase and also require trained engineers to interpret the data it collects. Meanwhile, the use of the site specific empirical formulas based on the real cases of pile driving and output analyses of the wave equation analysis programs can be beneficial. In the current study, pile driving data from three sites in the south of Iran were collected. Using the data of these cases and one-dimensional wave equation analysis program GRLWEAP, couple of experimental formulas which determine the proper range of hammer＇s ID for driving a pile, are proposed. Finally, due to the importance of the time in marine projects, another experimental formula is also proposed for estimation of the total driving time.展开更多
文摘There were for a long time two invariant forms of hydrodynamic equations： one was related to coordinate system of references, and the other was versus to measure units of characteristics. These both invariant forms had important roles in the development of theoretical and practical applications of hydro-aerodynamics and related industries. The third invariant form of hydrodynamic equations is one for the dimensions of spaces. For this goal, the hyper quantities （space and physics） are introduced. Then these are created we can easily cover all problems in arbitrary dimensions （3D, 2D, 1D, separate space for liquids or constituent matters）. In particularly, when they are applied to water hammer problem, which is an especially problem, we can receive immediately celerity and pressure of the event.
基金Universiti Kebangsaan Malaysia grant UKM-KK-03-FRGS 0118-2010Universiti Teknikal Malaysia Melaka for supporting these research activities
文摘An effective and simple way to develop equations from impact strain signals was proposed.Little research has been performed in this area,but this equation is very important for evaluating input signals in finite element analysis impact tests and for obtaining additional information on material deformation and fracture processes under impact loading.For this purpose,dynamic impact responses were examined through signals obtained from a strain gauge installed on an impact striker connected to a data acquisition system.Aluminium 6061-T6 was used to extract strain responses on the striker during Charpy impact testing.Statistical analysis was performed using the I-kaz method,and curve fitting equations based on the equation for vibration response under a non-periodic force were used to evaluate the Charpy impact signals.The I-kaz coefficients and curve fitting equations were then compared and discussed with related parameters,such as velocities and thicknesses.Velocity and thickness were found to be related to the strain signal patterns,curve fitting equations and I-kaz coefficients.The equations developed using this method had R2 values greater than 97.7%.Finally,the constructed equations were determined to be suitable for evaluating Charpy impact strain signal patterns and obtaining additional information on fracture processes under impact loading.
文摘There are various methods for analyzing pile driving process such as dynamic formulas, wave equation analyses and dynamic measurements. The programs of the two latter methods are relatively expensive to purchase and also require trained engineers to interpret the data it collects. Meanwhile, the use of the site specific empirical formulas based on the real cases of pile driving and output analyses of the wave equation analysis programs can be beneficial. In the current study, pile driving data from three sites in the south of Iran were collected. Using the data of these cases and one-dimensional wave equation analysis program GRLWEAP, couple of experimental formulas which determine the proper range of hammer＇s ID for driving a pile, are proposed. Finally, due to the importance of the time in marine projects, another experimental formula is also proposed for estimation of the total driving time.
