The Experts below are selected from a list of 303 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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Novel model for mean stress effect on high-cycle fatigue performance of threaded Fasteners
Journal of Advanced Joining Processes, 2020Co-Authors: Sayed A. Nassar, Mohamad El-zeinAbstract:Abstract An experimentally validated fatigue model is proposed for the effect of mean stress on high-cycle fatigue performance of preloaded threaded Fasteners. The proposed model is compared with commonly used models by Goodman, Gerber, Morrow, Soderberg, and ASME-Elliptic (ASME B106.1M:1985). Fatigue S-N curves are experimentally generated at various mean stress levels for both commercially available (CA) threaded Fasteners (Class 10.9 and 12.9), as well as ultra-high strength (UHS) Fasteners (Class 14.8, 15.8 and 16.8). Proposed model prediction and test data show that at high levels of Fastener mean stress, the bainite microstructure of the ultra-high strength Fasteners has a clear detrimental effect on Fastener fatigue performance, as compared to the martensite microstructure of commercially available low carbon steel Fasteners. Further discussion of test-validated model predictions and conclusions are provided.
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Clamp Load Loss due to Elastic Interaction and Gasket Creep Relaxation in Bolted Joints
Journal of Pressure Vessel Technology, 2006Co-Authors: Sayed A. Nassar, Ali A. AlkelaniAbstract:An experimental study is presented in order to determine the clamp load loss due to elastic interaction and gasket creep relaxation in bolted joints. Studied parameters include the gasket material and thickness, bolt spacing, tightening sequence, Fastener grip length, and level of the Fastener preload. The joint is composed of two steel flanges and a gasket made of styrene butadiene rubber or flexible graphite. The flanges are fastened together using M12x1.75 Class 10.9 Fasteners. Force washers are used to monitor bolt tensions in real time. Four different gasket thicknesses of styrene butadiene rubber (1/16, 1/8, 3/16, and 1/4 in.) and two thicknesses of flexible graphite (1/16 and 1/8 in.) are considered. For the same bolt circle of the flange, the bolt spacing is varied by using a different number of bolts; spacing that corresponds to using three, five, or seven bolts is considered in this study. The effect of the tightening strategy is studied by using sequential, star, or simultaneous tightening patterns. Bolt tightening is accomplished by using either an electric digital torque wrench with various control options or by using a production-size multiple spindle fastening system that is capable of simultaneous tightening of all Fasteners. Experimental data is presented and analyzed, in order to study the effect of the various parameters on the clamp load loss due to the combined effect of elastic interaction and gasket creep relaxation at room temperature.
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An Experimental Study of Bearing and Thread Friction in Fasteners
Journal of Tribology, 2005Co-Authors: Sayed A. Nassar, H. El-khiamy, Qian Zou, Gary C. Barber, T. S. SunAbstract:An experimental procedure is proposed for studying the underhead and thread friction in Fasteners. The effective bearing friction radius, the underhead friction coefficient, and the thread friction coefficient are experimentally determined for Fasteners with standard hexagonal heads and for flanged head Fasteners. Hence, greater accuracy has been achieved in determining the value of the torque components that are consumed in overcoming friction in threaded Fasteners. This would lead to a more reliable torque-tension correlation and would enhance the safety and quality of bolted assemblies. A design of experiment procedure is presented in order to investigate the effect of Fastener material class, the thread pitch, and the Fastener size on thread friction coefficient. For the underhead bearing friction, an experimental model is presented in order to determine the effect of the radii ratio of the contact area on the bearing friction radius.
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An Experimental Study of Bearing and Thread Friction in Fasteners
ASME STLE 2004 International Joint Tribology Conference Parts A and B, 2004Co-Authors: Sayed A. Nassar, H. El-khiamy, Qian Zou, Gary Barber, T. S. SunAbstract:An experimental procedure is proposed for studying the underhead and thread friction in Fasteners. The effective bearing friction radius, the underhead friction coefficient, and the thread friction coefficient are experimentally determined for Fasteners with standard hexagonal heads and for flanged head Fasteners. Hence, greater accuracy has been achieved in determining the value of the torque components that are consumed in overcoming friction in threaded Fasteners. This would lead to a more reliable torque-tension correlation and would enhance the safety and quality of bolted assemblies. A Design of Experiment (DOE) procedure is presented in order to investigate the effect of Fastener material class, the thread pitch, and the Fastener size on thread friction coefficient. For the underhead bearing friction, an experimental model is presented in order to determine the effect of the contact area radii ratio on the bearing friction radius.Copyright © 2004 by ASME
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Handbook of bolts and bolted joints
1998Co-Authors: John H. Bickford, Sayed A. NassarAbstract:MATERIAL PROPERTIES AND SELECTION Fastener Materials, A.C. Hood Joining with Aluminum Alloy Bolts and Nuts, R.E. Mack Thread Lubricants, G. Novak and T. Patel Adhesives and Sealants for Bolting, J. Cocco PROCESSING OF FastenerS Fastener Manufacturing, J.A. Phebu and P.K. Kasp Fastener Coatings, J. Laurillard Fastener Quality, C.B. Wackrow THREADED FastenerS Screw Threads, E. Schwartz and J.H. Bickford Fasteners Head Markings, C. Wilson Computing the Strength of a Fastener, J. Barron Computing the Stiffness of a Fastener, J. Barron Metric Fasteners, B. Marbacher Washers: A Guide to Their Function and Selection, M. Levinson Belleville Springs, G. Davet Vibration-Resistant Fasteners, J.R. Dudley Concrete Anchors, R.L. Zink Aerospace Bolts, S. Sadri DESIGN AND ANALYSIS OF BOLTED JOINTS VDI Joint Design Procedures, A.W. Heston Design of Gasketed Joints, B.S. Nau ASME Boiler and Pressure Vessel Code Design Rules for Bolted Flanges, G. Bibel Design of Joints Loaded in Shear, R.T. Barrett Design Rules for Structural Steel Bolting, J.H. Bickford and W.A. Milek ASSEMBLY OF BOLTED JOINTS Behavior of a Bolted Joint During Assembly, J.H. Bickford Tightening Groups of Fasteners in a Structure and the Resulting Elastic Interaction, G. Bibel Hydraulically Powered Wrenches, G. Sturdevant Hydraulic Stud Tensioning, W. Biach The Multi-Jackbolt Tensioning System, R.H. Steinbock Selecting Fastening Strategies and Equipment for Mass Production, J.R. Bippus Torque Control of Assembly, J.H. Bickford Stretch Control, R. Corbett Increasing Joint Performance by Tightening Bolts to Yield, P.W. Wallace Torque-Angle-Tension Control, R.S. Shoberg Control with Direct Tension Indicators, D. Sharp Use of Ultrasonics in Bolted Joints, S. Nassar Selecting Preload for an Existing Joint, J. H. Bickford THE JOINT IN SERVICE Joint Diagrams, J.H. Bickford Bolt Fatigue, F.R. Kull Corrosion, K.E. Yee The Susceptibility of Fasteners to Hydrogen Embrittlement and Stress Corrosion Cracking, L. Raymond Vibration-and Shock-Induced Loosening, D. Hess TESTING AND INSPECTION OF BOLTS AND JOINTS Statistical Design and Analysis of Multivariable Experiments, B. Clement Field Testing of Structural Bolts and Installation Tools Using a Bolt Tension Calibrator, J. Wilhelm Torque-Tension Audits, R. Shoberg EDUCATION AND TRAINING Fastening Technology Education, B. Blendu
T. S. Sun - One of the best experts on this subject based on the ideXlab platform.
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An Experimental Study of Bearing and Thread Friction in Fasteners
Journal of Tribology, 2005Co-Authors: Sayed A. Nassar, H. El-khiamy, Qian Zou, Gary C. Barber, T. S. SunAbstract:An experimental procedure is proposed for studying the underhead and thread friction in Fasteners. The effective bearing friction radius, the underhead friction coefficient, and the thread friction coefficient are experimentally determined for Fasteners with standard hexagonal heads and for flanged head Fasteners. Hence, greater accuracy has been achieved in determining the value of the torque components that are consumed in overcoming friction in threaded Fasteners. This would lead to a more reliable torque-tension correlation and would enhance the safety and quality of bolted assemblies. A design of experiment procedure is presented in order to investigate the effect of Fastener material class, the thread pitch, and the Fastener size on thread friction coefficient. For the underhead bearing friction, an experimental model is presented in order to determine the effect of the radii ratio of the contact area on the bearing friction radius.
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An Experimental Study of Bearing and Thread Friction in Fasteners
ASME STLE 2004 International Joint Tribology Conference Parts A and B, 2004Co-Authors: Sayed A. Nassar, H. El-khiamy, Qian Zou, Gary Barber, T. S. SunAbstract:An experimental procedure is proposed for studying the underhead and thread friction in Fasteners. The effective bearing friction radius, the underhead friction coefficient, and the thread friction coefficient are experimentally determined for Fasteners with standard hexagonal heads and for flanged head Fasteners. Hence, greater accuracy has been achieved in determining the value of the torque components that are consumed in overcoming friction in threaded Fasteners. This would lead to a more reliable torque-tension correlation and would enhance the safety and quality of bolted assemblies. A Design of Experiment (DOE) procedure is presented in order to investigate the effect of Fastener material class, the thread pitch, and the Fastener size on thread friction coefficient. For the underhead bearing friction, an experimental model is presented in order to determine the effect of the contact area radii ratio on the bearing friction radius.Copyright © 2004 by ASME
Stephen R Sharp - One of the best experts on this subject based on the ideXlab platform.
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evaluation of stainless steel Fasteners for bolted field splice connections of astm a1010 corrosion resistant steel plate girders
Transportation Research Record, 2017Co-Authors: Thomas R Williams, Xuemeng Xia, Thomas E Darby, Stephen R SharpAbstract:The Virginia Department of Transportation, Richmond, initiated this study to compare the mechanical properties, availability, and costs of stainless steel Fastener materials for use with ASTM A1010 stainless steel plate. The investigation focused on Fastener materials included in ASTM A193 and compared them with ASTM A325 bolts. The ASTM A193 bolts tested were the B6, B8, and B8M. Test results indicated that the ASTM A193 B8 Fasteners provided the most economic combination of mechanical strength, corrosion resistance, and cost. Uniaxial tension tests and Skidmore–Wilhelm rotational capacity tests revealed that the B6 Fasteners had high strength but lower ductility, whereas the B8M Fasteners had lower strength but higher ductility. The B8 Fastener had an ideal combination of strength and ductility. The mechanical performance of the ASTM A193 Fasteners was improved further by the use of hardened washers. Because the bolts are hot forged, sensitization, which can reduce corrosion resistance, was of concern. ...
H Fujii - One of the best experts on this subject based on the ideXlab platform.
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an anti loosening screw Fastener innovation and its evaluation
Journal of Materials Processing Technology, 1998Co-Authors: N Sase, S. Koga, K. Nishioka, H FujiiAbstract:Abstract It is widely known that screw Fasteners loosen sooner or later, even so-called anti-loosening screw Fasteners available in the market do not prevent loosening, as reported in an earlier paper. The purpose of this paper is to present the development of a real anti-loosening screw Fastener that has a strong resistance against loosening without sacrificing any of the advantageous features of conventional screw Fasteners. Before introducing the development, the mechanism of the loosening process of screw Fasteners is investigated. It is shown that the loosening of screw Fasteners is caused by two factors. One is relative slip between the bolt and nut screw threads, the slip causing torsion in the bolt. The other is relative slip between the bearing surface of the bolt or nut and the surface of the fastened material, the slip causing slackening of the torsion. The prevention of loosening should be possible if either one of these causes is eliminated. Aiming at eliminating the first cause, the torsion, a new screw named `The Step-Lock Bolt' (SLB) is developed. The developed bolt has eight steps in which the lead angle degree is nil at the circumference of the thread. The efficacy in preventing the initiation and progress of loosening is examined by applying a force cyclically at right angles to the center line of a bolt. The results show that whilst a conventional Fastener lost the fastening force within 1000 cycles, the developed SLB does not lose the fastening force until over 30 000 cycles. It may thus be concluded that the SLB is a practical means of preventing screw Fastener loosening.
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evaluation of anti loosening nuts for screw Fasteners
Journal of Materials Processing Technology, 1996Co-Authors: N Sase, S. Koga, K. Nishioka, H FujiiAbstract:Abstract There are various types of screw Fasteners and/or parts with additional features designed to prevent loosening. Their actual ability is questioned and concretely examined. Seven types of those so-called anti-loosening nuts which are readily available in the market are compared with conventional nuts and evaluated their ability, including their manoeuvrability. Two types of loosening devices are developed for this purpose. One is to loosen Fasteners by forcing a fastened material to displace and the other by applying high acceleration to a whole structure. The conclusions obtained are as follows: (1) Nuts with edged spring at the bottom, nylon inserted nuts, metal inserted nuts and rings with sharp inner edge to cover nuts are all unable to stop loosening. (2) A nut with serrated flange at the bottom has the ability to suppress the initiation of loosening to some extent. It makes the Fastener resistant to higher levels of acceleration than fine screws. (3) A pair of double nuts and a combination of a nut with an eccentric external taper and a nut with an internal taper can slow the loosening process considerably. The latter may be an answer at present, but it is effective only under limited conditions.
Qingzhou Mao - One of the best experts on this subject based on the ideXlab platform.
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a rigorous Fastener inspection approach for high speed railway from structured light sensors
Isprs Journal of Photogrammetry and Remote Sensing, 2017Co-Authors: Qingzhou Mao, Qingwu Hu, Hao Cui, Xiaochun RenAbstract:Abstract Rail Fasteners are critical components in high-speed railway. Therefore, they are inspected periodically to ensure the safety of high-speed trains. Manual inspection and two-dimensional visual inspection are the commonly used methods. However, both of them have drawbacks. In this paper, a rigorous high-speed railway Fastener inspection approach from structured light sensors is proposed to detect damaged and loose Fasteners. Firstly, precise and extremely dense point cloud of Fasteners are obtained from commercial structured light sensors. With a decision tree classifier, the defects of the Fasteners are classified in detail. Furthermore, a normal vector based center extraction method for complex cylindrical surface is proposed to extract the centerline of the metal clip of normal Fasteners. Lastly, the looseness of the Fastener is evaluated based on the extracted centerline of the metal clip. Experiments were conducted on high-speed railways to evaluate the accuracy, effectiveness, and the influence of the parameters of the proposed method. The overall precision of the decision tree classifier is over 99.8% and the root-mean-square error of looseness check is 0.15 mm, demonstrating a reliable and effective solution for high-speed railway Fastener maintenance.