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C&G Unit 204: Installation of wiring systems and enclosures
Published in Trevor Linsley, Basic Electrical Installation Work, 2018
The torque screwdriver is becoming increasingly popular in the electrical industry. A torque screwdriver is a screwdriver with an in-built mechanism to ensure that the screw can be tightened to a specified, pre-set torque or turning force. This ensures that tightening is sufficient to make a safe electrical connection, but not so excessive as to cause damage to the screw thread.
Notched specimen cracking test: a novel method to directly measure low-temperature thermal stress of asphalt binder
Published in International Journal of Pavement Engineering, 2022
Haoyuan Luo, Rongyan Tian, Yangzezhi Zheng, Dalin Wang, Siyu Chen, Xiaoming Huang
After removing the binder specimen from the silicone mould, it should be installed on the fixtures immediately, which should be carried out as quickly and carefully as possible to prevent its deformation and causing excessive deformation or stress concentrations. The operations of installing the binder specimen are as follows seen in Figure 9: Set the gap between the upper and lower fixture as 25 mm.Place the binder specimen with the aluminium end pieces into the recessed positions in the fixtures and keep the center line of its long axis aligned with the center line of fixtures (red dotted line in Figure 9(a)).Buckle the clamping pieces on the aluminium end pieces of the binder specimen and embed the binder specimen within the recessed positions in middle of clamping pieces.Tight the screws to let the clamping pieces and fixtures clamp the binder specimen. It is best to use a torque screwdriver for tightening with the same torque, which can prevent mounting stresses in the binder specimen effectively.Examine the specimen to ensure that it exhibits neither wrinkles nor kinks. If these are present the specimen should be reinstalled.
Prediction of Orthotropic Thermal Conductivities Using Bayesian-Inference from Experiments under Vacuum Conditions
Published in Heat Transfer Engineering, 2023
Suraj Kumar, Chakravarthy Balaji
Using fasteners and fixtures, the test samples (isotropic and orthotropic), heater, copper ring, and cold plate are assembled. With a torque screwdriver, fixtures are provided with Teflon coating at their ends, and are torqued to supply uniform pressure overall contact surfaces and fasteners.To increase the interface touch conductance, silicone-based thermal grease is applied on all the interfaces.The whole assembly is placed within the vacuum chamber over a Teflon stand.The heater wires and the thermocouple are then connected to the data logger and the DC power supply through the related vacuum-tight feed-throughs.The vacuum chamber is then fully closed, and vacuum pumps are switched on. A vacuum pressure of 8.6 × 10−7mbar vacuum is obtained, and a Pirani gauge is used to monitor this vacuum pressure.Using a DC power supply, the heater is then powered, and the cold fluid circulation began using a constant temperature bath (make: Julabo [28]) simultaneously. Following this, temperatures are measured for both the test samples using T-type thermocouples at the specified locations at time instants of 0, 5, 10, 15, 20, 25, 30, 35, and 40 minutes, and are recorded and stored in a data file.For those experiments involving steady-state, the latter is declared if the temperature does not change within the uncertainty of the thermocouples in 30 minutes. Thermocouples data are then recorded at prescribed locations.Steady and unsteady measured temperatures of the isotropic material are then used in the inverse technique to estimate the thermal conductivity and heat capacity of the isotropic material sequentially. Finally, the measured temperatures of the orthotropic material are used in the inverse framework to estimate the pricipal thermal conductivities of the orthotropic material from the unsteady experiments.The temperature measurement positions on the upper and bottom of the SS304 isotropic and orthotropic plate surfaces are shown in Figures 8 and 9, respectively. The measured temperatures are later used in the actual estimation process.