Hot tearing is one of the most serious defects during the casting solidification process.In this study,a new type of multichannel"cross"hot tearing device was designed.The hot cracks initiation and propagati...Hot tearing is one of the most serious defects during the casting solidification process.In this study,a new type of multichannel"cross"hot tearing device was designed.The hot cracks initiation and propagation were predicted by the relationship between temperature,shrinkage force and solidification time during the casting solidification process.The reliability and practicability of the multichannel"cross"hot tearing device were verified by casting experiments and numerical simulations.The theoretical calculation based on Clyne-Davies model and numerical simulation results show that the hot tearing tendency decreases in the order:2024 Al alloy>Al-Cu alloy>Al-Si alloy at a pouring temperature of 670°C and a mold temperature of 25°C.Feeding of liquid films at the end of solidification plays an important role in the propagation process of hot tearing.The decrease of hot tearing tendency is attributed to the feeding of liquid film and intergranular bridging.展开更多
The current study is based on the DEM computer simulation of three experimental test devices with different dimensions to determine the difference in the results of the formation of shear and repose angles that the pa...The current study is based on the DEM computer simulation of three experimental test devices with different dimensions to determine the difference in the results of the formation of shear and repose angles that the particles experience when grouped under the action of the gravitational force. In this respect, the experimental test devices with different height, width, and depth were geometrically modeled with iron pellet particles using morphology and a granulometric variation from 6 mm to 9 mm of equivalent diameter in its spherical shape. Depending on the results obtained, a reliable size of the experimental test device will be available to obtain the necessary data for a correct adjustment of the calibration parameters for the DEM simulation of mining-metallurgical processes that use granulated material of iron pellet.展开更多
As a core part of subsea production systems,subsea control modules(SCMs)are costly,difficult,and expensive to install and inconvenient to use in underwater maintenance.Therefore,performance and function tests must be ...As a core part of subsea production systems,subsea control modules(SCMs)are costly,difficult,and expensive to install and inconvenient to use in underwater maintenance.Therefore,performance and function tests must be carried out before launching SCMs.This study developed a testing device and an SCM test by investigating SCMs and their underwater.The testing device includes four parts:a hydraulic station,an SCM test stand,a signal generating device,and an electronic test unit.First,the basic indices of the testing device were determined from the performance and working parameters of the SCM.Second,the design scheme of the testing device for the SCM was tentatively proposed,and each testing device was designed.Finally,a practical measurement of the SCM,in combination with the hydraulic station,SCM test stand,signal generator,electronic unit,and highpressure water tank,was carried out according to the test requirements.The measurement mainly involved equipment inspection before testing and an experimental test for the SCM.The validity and feasibility of the testing device and method were simultaneously verified through an association test.展开更多
Forensic biomechanics gradually has become a significant component of forensic science.Forensic biomechanics is evidence-based science that applies biomechanical principles and methods to forensic practice,which has c...Forensic biomechanics gradually has become a significant component of forensic science.Forensic biomechanics is evidence-based science that applies biomechanical principles and methods to forensic practice,which has constituted one of the most potential research areas.in this review,we introduce how finite element techniques can be used to simulate forensic cases,how injury criteria and injury scales can be used to describe injury severity,and how tests of postmortem human subjects and dummy can be used to provide essential validation data.This review also describes research progress and new applications of forensic biomechanics in China.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.51875365).
文摘Hot tearing is one of the most serious defects during the casting solidification process.In this study,a new type of multichannel"cross"hot tearing device was designed.The hot cracks initiation and propagation were predicted by the relationship between temperature,shrinkage force and solidification time during the casting solidification process.The reliability and practicability of the multichannel"cross"hot tearing device were verified by casting experiments and numerical simulations.The theoretical calculation based on Clyne-Davies model and numerical simulation results show that the hot tearing tendency decreases in the order:2024 Al alloy>Al-Cu alloy>Al-Si alloy at a pouring temperature of 670°C and a mold temperature of 25°C.Feeding of liquid films at the end of solidification plays an important role in the propagation process of hot tearing.The decrease of hot tearing tendency is attributed to the feeding of liquid film and intergranular bridging.
文摘The current study is based on the DEM computer simulation of three experimental test devices with different dimensions to determine the difference in the results of the formation of shear and repose angles that the particles experience when grouped under the action of the gravitational force. In this respect, the experimental test devices with different height, width, and depth were geometrically modeled with iron pellet particles using morphology and a granulometric variation from 6 mm to 9 mm of equivalent diameter in its spherical shape. Depending on the results obtained, a reliable size of the experimental test device will be available to obtain the necessary data for a correct adjustment of the calibration parameters for the DEM simulation of mining-metallurgical processes that use granulated material of iron pellet.
基金supported by the National Key R&D Program of China(2018YFC0310500)High-Tech Ship Research Projects sponsored by the Ministry of Industry and Information Technology(2018GXB01)Yantai City school land integration development project(2019XDRHXMPT29)research and development and test platform of underwater production system。
文摘As a core part of subsea production systems,subsea control modules(SCMs)are costly,difficult,and expensive to install and inconvenient to use in underwater maintenance.Therefore,performance and function tests must be carried out before launching SCMs.This study developed a testing device and an SCM test by investigating SCMs and their underwater.The testing device includes four parts:a hydraulic station,an SCM test stand,a signal generating device,and an electronic test unit.First,the basic indices of the testing device were determined from the performance and working parameters of the SCM.Second,the design scheme of the testing device for the SCM was tentatively proposed,and each testing device was designed.Finally,a practical measurement of the SCM,in combination with the hydraulic station,SCM test stand,signal generator,electronic unit,and highpressure water tank,was carried out according to the test requirements.The measurement mainly involved equipment inspection before testing and an experimental test for the SCM.The validity and feasibility of the testing device and method were simultaneously verified through an association test.
基金The study was financially supported by grants from the National Key Research and Development Plan[grant number 2016YFC0800702]Council of National Science Foundation of China[grant numbers 81701863,81722027]+3 种基金Shanghai Key Laboratory of Forensic Medicine[grant number 17DZ2273200]Shanghai Forensic Service Platform[grant number 19DZ2290900]Central Research Institute Public Project[grant numbers GY2020G4,GY2019Z2]Opening Project of Shanghai Key Laboratory of Crime Scene Evidence[grant number 2019XCWZK03].
文摘Forensic biomechanics gradually has become a significant component of forensic science.Forensic biomechanics is evidence-based science that applies biomechanical principles and methods to forensic practice,which has constituted one of the most potential research areas.in this review,we introduce how finite element techniques can be used to simulate forensic cases,how injury criteria and injury scales can be used to describe injury severity,and how tests of postmortem human subjects and dummy can be used to provide essential validation data.This review also describes research progress and new applications of forensic biomechanics in China.