Search Results for fastened joints

This article discusses the effect of thread design, preload, tightening, and mean stress on the fatigue strength of bolt steel. It describes the factors influencing fatigue failures in cold-driven and hot-driven riveted joints. The factors affecting the fatigue resistance of bolted friction joints are also discussed. The article reviews stress concentrations in pin joints and discusses stress-intensity factors for mechanically fastened joints.

This article provides a discussion on adhesively bonded joints and elastic-plastic mathematical model for an adhesive in shear. It discusses the design rules for thin bonded structures and reviews computer programs for the highly loaded stepped-lap joints. The article describes the two-dimensional effects associated with load redistribution around flaws and with damage tolerance. The elastic-isotropic geometric stress-concentration factors and empirically established correlation factors of mechanically fastened joints are discussed. The article provides information on the identification of optimal joint proportions for single-row joints, and the design and analysis of the stronger multirow joints, with particular regard to the bearing-bypass interaction.

This article provides an overview of the relationships between torque, angle-of-turn, tension, and friction and explains how they are measured and evaluated. It focuses on the principle, test equipment, procedure, evaluation, and test report of various testing methods, namely, friction coefficient testing, torque tension testing, locknut testing, and angular ductility and rotational capacity tests. The article reviews the basic methods and fundamental principles for mechanical testing of externally and internally threaded fasteners and bolted joints. The test methods for externally threaded fasteners include product hardness, proof load, axial and wedge tension testing of full-sized products, tension testing of machined test specimens, and total extension at fracture testing. Product hardness, proof load, and cone proof-load test are the test methods for internally threaded fasteners. The article concludes with a description of torque-angle signature analysis and the specification of measurement accuracy for torque and clamp force.

Environmental effects of ground and flight environments, including temperature extremes, damage by chemical fluids, moisture, and so forth, affect the durability of polymer-matrix composites. This article provides information on corrosion control methods in aircraft structures. It discusses the design considerations for sealants in joints. The article describes the common methods to seal aircraft structures: fay surface, fillet, butt joint, channel, brush, and form-in-place seals. It discusses the surface preparation and application method of primer and topcoat systems. Primer and paint application equipment as well as sealant application equipment are reviewed.

This article explores why structural element and subcomponent testing are conducted. It discusses the different types of failure modes in composites, and provides information on the testing methodology, fixturing, instrumentation, and data reporting. The article reviews various standard elements used to characterize composite materials for the various failure modes. Simple structural-element testing under in-plane unidirectional, multidirectional, and combined loading, as well as out-of-plane loading are discussed. Simple bolted and bonded joints, as well as data correlation are reviewed with analytical predictions. The article also provides a list of the ASTM testing standards applicable at the element level of testing for both polymer-matrix composites and metal-matrix composites. It concludes with a discussion on durability and damage tolerance testing.

The structural efficiency of a composite structure is established by its joints and assembly. Adhesive bonding, mechanical fastening, and fusion bonding are three types of joining methods for polymer-matrix composites. This article provides information on surface treatment and the applications of adhesive bonding. It discusses the types of adhesives, namely, epoxy adhesives, epoxy-phenolic adhesives, condensation-reaction PI adhesives, addition-reaction PI adhesives, bismaleimide adhesives, and structural adhesives. The article provides information on fastener selection considerations, including corrosion compatibility, fastener materials and strength, head configurations, importance of clamp-up, interference fit fasteners, lightning strike protection, blind fastening, and sensitivity to hole quality. Types of fusion bonding are presented, namely, thermal welding, friction welding, electromagnetic welding, and polymer-coated material welding.

This article discusses three typical repair types for composite structures: temporary repairs, adhesively bonded repairs, and bolted repairs. It contains a table that lists general design requirements and considerations for the repair of composite structures. The article describes ten steps for an engineering repair approach to effectively restore structural integrity to damaged composite components. Management, validation and certification of repairs are also discussed. The article presents the design guidelines for analyzing the damage and possible strategies for making a repair. It reviews three repair schemes used in repair design analysis, namely, core replacement, adhesively bonded patch, and mechanically fastened patch. The article also emphasizes the various pitfalls and problems in repair design for composite structures.

Joining is key to the manufacture of large or complex devices or assemblies; construction of large and complex structures; and repair of parts, assemblies, or structures in service. This article describes the three forces for joining: physical, chemical, and mechanical. It provides an overview of the joining processes, namely, mechanical fastening, integral attachment, adhesive bonding, welding, brazing, and soldering. The article concludes with information on the various aspects of joint design and location that determine the selection of a suitable joining method.

Advanced thermoplastic composites possess impact resistance, fracture toughness, and elevated temperature endurance properties due to their melt-fusible nature. This article presents the material options available for thermoplastic composites such as pseudothermoplastics, post-impregnated thermoplastics, and true thermoplastics. It describes the processing methods of thermoplastic composites, including weaving, seaming, autoclaving, preconsolidation, roll consolidation, roll forming/pultruding, thermoforming, press forming, hydroforming, and diaphragm forming. The article provides information on different types of joints, namely, fastened, adhesive bonded, dual polymer bonded, co-consolidated, and welded joints. It explains the joining methods of thermoplastic composites, such as press forming, diaphragm forming, autoclaving, ultrasonic welding, resistance welding, and induction welding.

This article discusses different types of mechanical fasteners, including threaded fasteners, rivets, blind fasteners, pin fasteners, special-purpose fasteners, and fasteners used with composite materials. It describes the origins and causes of fastener failures and with illustrative examples. Fatigue fracture in threaded fasteners and fretting in bolted machine parts are also discussed. The article provides a description of the different types of corrosion, such as atmospheric corrosion and liquid-immersion corrosion, in threaded fasteners. It also provides information on stress-corrosion cracking, hydrogen embrittlement, and liquid-metal embrittlement of bolts and nuts. The article explains the most commonly used protective metal coatings for ferrous metal fasteners. Zinc, cadmium, and aluminum are commonly used for such coatings. The article also illustrates the performance of the fasteners at elevated temperatures and concludes with a discussion on fastener failures in composites.

This article first provides an overview of the types of mechanical fasteners. This is followed by sections providing information on fastener quality and counterfeit fasteners, as well as fastener loads. Then, the article discusses common causes of fastener failures, namely environmental effects, manufacturing discrepancies, improper use, or incorrect installation. Next, it describes fastener failure origins and fretting. Types of corrosion in threaded fasteners and their preventive measures are then covered. The performance of fasteners at elevated temperatures is addressed. Further, the article discusses the types of rivet, blind fastener, and pin fastener failures. Finally, it provides information on the mechanism of fastener failures in composites.

This article compares and contrasts mechanical joining techniques used in the manufacture of aluminum assemblies, including seaming, swaging, flanging, crimping, clinching, dimpling, interference and snap fits, and interlocking joints. It provides basic illustrations of the various methods and summarizes the advantages and disadvantages of each. The article also discusses the use of staples, nails, rivets, and threaded fasteners and provides relevant property and performance data.

Detailed analyses and test correlations are typically required to support design development, structural sizing, and certification. This article addresses issues concerning building block levels ranging from design-allowables coupons up through subcomponents, as these levels exhibit a wide variety of test-analysis correlation objectives. At these levels, enhanced analysis capability can be used most effectively in minimizing test complexity and cost while also reducing design weight and risk. The article discusses the examples of tests for which good correlative capability has shown significant benefit. These include notched (open and/or filled hole) tension and compression, inter/intralaminar shear and tension, and pin bearing.

This article focuses on the factors to be considered for selecting fasteners for joining carbon fiber composites. These considerations include corrosion compatibility, fastener materials, strength, stiffness, head configurations, importance of clamp-up, hole fit, and lightning protection.

This article discusses different types of joining processes, including welding, brazing, soldering, mechanical fastening, and adhesive bonding. It examines two broad classes of welding: fusion welding and solid-state welding. The article discusses the process selection considerations for welding, brazing, and soldering. It also describes joint design considerations such as selection of weld joints and welds.