The Experts below are selected from a list of 18 Experts worldwide ranked by ideXlab platform
Sayed A. Nassar - One of the best experts on this subject based on the ideXlab platform.
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EFFECT OF FASTENER UNDER HEAD CONTACT ON THE EARLY STAGE OF SELF- LOOSENING OF PRELOADED COUNTERSUNK FASTENERS SUBJECTED TO CYCLIC SHEAR LOADING
2015Co-Authors: Amro M Zaki, Sayed A. NassarAbstract:Three dimensional Finite Element model is used to investigate the loosening behavior of countersunk threaded fasteners subjected to cyclic shear loading applied through prescribed transverse excitation to the fastener head. Fasteners with conical head profile require precision machining of both the fastener head and the mating joint Hole. Any mismatch between the head and the joint conical angles affects the torque tension relationship as well as the loosening performance. Investigation focuses on the loosening behavior in its early stages. Factors investigated include the effect of the bolt head/joint Hole contact location, joint elastic modulus, and Tapped Hole clearance for different combinations of thread fit, on the loosening performance of preloaded countersunk-head bolts. The FEA model prediction of the self-loosening behavior is experimentally validated
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effect of fastener under head contact on the early stage of self loosening of preloaded countersunk fasteners subjected to cyclic shear loading
ASME 2014 Pressure Vessels and Piping Conference, 2014Co-Authors: Amro M Zaki, Sayed A. NassarAbstract:Three dimensional Finite Element model is used to investigate the loosening behavior of countersunk threaded fasteners subjected to cyclic shear loading applied through prescribed transverse excitation to the fastener head. Fasteners with conical head profile require precision machining of both the fastener head and the mating joint Hole. Any mismatch between the head and the joint conical angles affects the torque tension relationship as well as the loosening performance. Investigation focuses on the loosening behavior in its early stages. Factors investigated include the effect of the bolt head/joint Hole contact location, joint elastic modulus, and Tapped Hole clearance for different combinations of thread fit, on the loosening performance of preloaded countersunk-head bolts. The FEA model prediction of the self-loosening behavior is experimentally validated.Copyright © 2014 by ASME
Amro M Zaki - One of the best experts on this subject based on the ideXlab platform.
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EFFECT OF FASTENER UNDER HEAD CONTACT ON THE EARLY STAGE OF SELF- LOOSENING OF PRELOADED COUNTERSUNK FASTENERS SUBJECTED TO CYCLIC SHEAR LOADING
2015Co-Authors: Amro M Zaki, Sayed A. NassarAbstract:Three dimensional Finite Element model is used to investigate the loosening behavior of countersunk threaded fasteners subjected to cyclic shear loading applied through prescribed transverse excitation to the fastener head. Fasteners with conical head profile require precision machining of both the fastener head and the mating joint Hole. Any mismatch between the head and the joint conical angles affects the torque tension relationship as well as the loosening performance. Investigation focuses on the loosening behavior in its early stages. Factors investigated include the effect of the bolt head/joint Hole contact location, joint elastic modulus, and Tapped Hole clearance for different combinations of thread fit, on the loosening performance of preloaded countersunk-head bolts. The FEA model prediction of the self-loosening behavior is experimentally validated
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effect of fastener under head contact on the early stage of self loosening of preloaded countersunk fasteners subjected to cyclic shear loading
ASME 2014 Pressure Vessels and Piping Conference, 2014Co-Authors: Amro M Zaki, Sayed A. NassarAbstract:Three dimensional Finite Element model is used to investigate the loosening behavior of countersunk threaded fasteners subjected to cyclic shear loading applied through prescribed transverse excitation to the fastener head. Fasteners with conical head profile require precision machining of both the fastener head and the mating joint Hole. Any mismatch between the head and the joint conical angles affects the torque tension relationship as well as the loosening performance. Investigation focuses on the loosening behavior in its early stages. Factors investigated include the effect of the bolt head/joint Hole contact location, joint elastic modulus, and Tapped Hole clearance for different combinations of thread fit, on the loosening performance of preloaded countersunk-head bolts. The FEA model prediction of the self-loosening behavior is experimentally validated.Copyright © 2014 by ASME
Ratzmann Paul - One of the best experts on this subject based on the ideXlab platform.
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D0 Silicon Upgrade: Thermal Conductivity Measurements of a Variety of Epoxies and Greases Used for CDF/D0 Silicon Detector Ladder Construction
Fermi National Accelerator Laboratory, 1996Co-Authors: Gillespie Gordie, Jostlein Hans, Ratzmann PaulAbstract:The bulk thermal conductivity of several epoxy mixtures was measured with a setup at Lab D. Samples are prepared by using two aluminum cylinders of 3/4-inch diameter. The cylinders have Holes drilled in them for insertion of temperature sensors (0.040-inch diameter thermistors), a heating element (standard resistor), and a Tapped Hole for heat sinking to a plate. The two cylinders are held together during gluing, and the thickness of the glue bead is controlled by using a shim of kapton tape, nominally 3.5 mils thickness per ply of tape. A resistor is glued into the Hole using 5 minute epoxy. Care is taken to avoid shorting the leads to the aluminum cylinder. Once the sample is prepared, the sample is fixed to the heat sink using the Tapped Hole provided. Thermistors are carefully inserted into the four Holes. Once set up, the data acquisition program is run for a half-hour prior to turning on the heater power. This is done to ensure that all temperatures stabilize, and this is checked when doing the analysis. The power is then turned on and run until the temperatures have stabilized, which takes two additional hours. The data acquisition program outputs the four measured temperatures in the form of a voltage. which is read across the thermistor. With known temperatures, a known geometry, and known joint thickness, the temperature drop across the joint can be extrapolated and the bulk thermal conductivity of the interface material can be calculated. The power is measured directly using an ammeter in series with the power supply, and measuring the voltage across the resistor while powered up. The resistor value is measured using a hand held device in order to cross-correlate the measurements. The voltage and current are independently measured using the data acquisition program. Their product has been consistently found to be a factor of 10.7 {+-} 0.1 lower than the manual measurement of power and has proven to be a good cross-check to the measurement of the power dissipation (the current and voltage readouts to the acquisition program are stepped down with series and parallel resistors, hence off by a factor). The gradient within the aluminum yields the thermal conductivity of the aluminum, knowing the power and geometry of the piece. The measured aluminum conductivity has been consistently 207 W/m-K with a standard deviation of 13 W/m-K for a large number of measurements, in good agreement with published values. This calculation provides additional cross-check as to the validity of the measurement
Gillespie Gordie - One of the best experts on this subject based on the ideXlab platform.
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D0 Silicon Upgrade: Thermal Conductivity Measurements of a Variety of Epoxies and Greases Used for CDF/D0 Silicon Detector Ladder Construction
Fermi National Accelerator Laboratory, 1996Co-Authors: Gillespie Gordie, Jostlein Hans, Ratzmann PaulAbstract:The bulk thermal conductivity of several epoxy mixtures was measured with a setup at Lab D. Samples are prepared by using two aluminum cylinders of 3/4-inch diameter. The cylinders have Holes drilled in them for insertion of temperature sensors (0.040-inch diameter thermistors), a heating element (standard resistor), and a Tapped Hole for heat sinking to a plate. The two cylinders are held together during gluing, and the thickness of the glue bead is controlled by using a shim of kapton tape, nominally 3.5 mils thickness per ply of tape. A resistor is glued into the Hole using 5 minute epoxy. Care is taken to avoid shorting the leads to the aluminum cylinder. Once the sample is prepared, the sample is fixed to the heat sink using the Tapped Hole provided. Thermistors are carefully inserted into the four Holes. Once set up, the data acquisition program is run for a half-hour prior to turning on the heater power. This is done to ensure that all temperatures stabilize, and this is checked when doing the analysis. The power is then turned on and run until the temperatures have stabilized, which takes two additional hours. The data acquisition program outputs the four measured temperatures in the form of a voltage. which is read across the thermistor. With known temperatures, a known geometry, and known joint thickness, the temperature drop across the joint can be extrapolated and the bulk thermal conductivity of the interface material can be calculated. The power is measured directly using an ammeter in series with the power supply, and measuring the voltage across the resistor while powered up. The resistor value is measured using a hand held device in order to cross-correlate the measurements. The voltage and current are independently measured using the data acquisition program. Their product has been consistently found to be a factor of 10.7 {+-} 0.1 lower than the manual measurement of power and has proven to be a good cross-check to the measurement of the power dissipation (the current and voltage readouts to the acquisition program are stepped down with series and parallel resistors, hence off by a factor). The gradient within the aluminum yields the thermal conductivity of the aluminum, knowing the power and geometry of the piece. The measured aluminum conductivity has been consistently 207 W/m-K with a standard deviation of 13 W/m-K for a large number of measurements, in good agreement with published values. This calculation provides additional cross-check as to the validity of the measurement
P Y Manach - One of the best experts on this subject based on the ideXlab platform.
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characterization of ironing in the Hole flanging process of an aluminum alloy
THE 8TH INTERNATIONAL CONFERENCE AND WORKSHOP ON NUMERICAL SIMULATION OF 3D SHEET METAL FORMING PROCESSES (NUMISHEET 2011), 2011Co-Authors: Ahmed Hadj Kacem, Abdelkader Krichen, P Y ManachAbstract:Hole‐flanging is a sheet metal forming process which is often used to produce a flange around Holes. Many industrial applications require a longer flange that can be used for example to increase bearing surface or to increase the number of threads that will fit in a Tapped Hole. Ironing is usually used during such process to increase the flange height. Due to the thinning of the flange caused by edge stretching, some difficulties arise when trying to set a clearance value for which the process is performed with ironing. Therefore, the occurrence of ironing needs to be more clarified. It is also important to quantify the effect of ironing intensity in the flange geometry. In the present work, FE simulations and experiments are performed to investigate Hole‐flanging with and without ironing. For this purpose, Hole‐flanging is carried out by varying the clearance between the punch and the die while keeping constant the other parameters. The aim is to identify the occurrence of ironing by the determination of a limit between the Hole‐flanging with ironing and the Hole‐flanging without ironing. Attention is focused on studying the effect of the Hole‐flanging conditions on the punch load, the forming kinematics and the final shape. The experiments are carried out to check the FE results on an aluminum alloy.
