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Weapon Design Practice
Published in Donald E. Carlucci, Sidney S. Jacobson, Ballistics, 2018
Donald E. Carlucci, Sidney S. Jacobson
Jackets improve the efficiency of the gun tube by utilizing more of the materials load-carrying capacity. The design concept began around 1870 and has been in use since then, but is now considered obsolete. The idea is that one can shrink fit one or more cylinders over the inner cylinder or liner so that a compressive stress is induced in the inner layers. When an internal pressure is applied, the stresses on the inner cylinders are relieved by the pressure and then put into tension as the pressure is increased. Autofrettaging (self-jacketing) rather than shrink fitting is now the process in use.
Joining Applications
Published in Valery Rudnev, Don Loveless, Raymond L. Cook, Handbook of Induction Heating, 2017
Valery Rudnev, Don Loveless, Raymond L. Cook
During shrink fitting, the external (or encircling) component is heated to temporarily expand it, which enables insertion of the other component for a slip or snug fit at assembly. The assembly is then cooled to room temperature, resulting in a contraction of the external component permanently locking the parts together. Shrink fitting is a reversible process—components can be disassembled by reheating (if the parts were only press-fit together without heating, unacceptable deformation of the assembly could result). Motor housing disassembly can serve as an example of this application.
Influence of shrinkage loss on failure of an extrusion container associated with creep deformation
Published in Mechanics Based Design of Structures and Machines, 2022
Ling Ma, Yongqin Wang, Yuanxin Luo
Based on the results of cyclic extrusion simulation, crack would firstly emerge on the liner’s inner surface near the entrance of billet, which reaches its critical damage value of 0.19 after about 15600 extrusion cycles. Thus, analysis of shrinkage loss and creep deformation would be made during these 15600 extrusion cycles. Figure 5 shows creep strain of the EC during an extrusion cycle and SDV10 is a state variable defined in UMAT to represent the accumulated creep strain. It can be seen that creep strain on the bottom of inner surface of the liner is maximum. It's because this position experiences the longest contact time with billet. Furthermore, it accounts for the common phenomenon that the liner often suffers failure of excessive deformation of inner surface, which is ascribed to creep deformation. In addition, creep deformation around shrink fitting surfaces is also very significant and it’s obvious that creep deformation on the two fitting surfaces is not consistent, which would result in shrinkage loss. In fact, insufficient shrinkage would generate insufficient prestress and lead to axial endplay which is another failure mode of EC. Moreover, insufficient prestress would increase the stress level exerted on liner and decrease the support from outer layers, essentially make it easy to crack. Hence, considering these two main failure modes resulting from insufficient shrinkage, this chapter is divided into two parts to discuss the influence of shrinkage loss on failure of EC.
Effect of the Engagement Ratio and of Temperature on the Shear Strength of Epoxy Adhesive Bonded Aluminum Alloy Pin-and-Collar Joints
Published in The Journal of Adhesion, 2018
D. Croccolo, M. De Agostinis, S. Fini, G. Olmi
Nowadays, there is a growing interest towards the application of structural adhesives, such as epoxy or anaerobic glues. Many studies have indicated that the great potentials of these joining techniques arise from the reduction of weight, the increase of strength and the improvement of fatigue and fretting corrosion. When a shaft and a hub are joined by interference, particularly strict tolerances are required to be able to transmit high torques and power. As an effect, manufacturing and assembly costs may significantly increase, especially if thermal effects (heating or cooling) are required, to connect the mating parts by shrink-fitting. Moreover, a further drawback is that a particularly high circumferential tensile state of stress is generated in the hub. An anaerobic adhesive is particularly suitable to these types of joints, as it makes possible to reduce the amount of interference, thus simplifying the assembly procedure and reducing the stress induced in the hub. This outcome also improves the fatigue behaviour of the structure; moreover, the addition of the adhesive makes it possible to prevent the occurrence of corrosion fretting. [1] Several studies have been performed, to investigate the effect of a number of factors on the response of interference fitted and adhesively bonded joints. In particular, the effects of the following factors have been assessed: the assembly pressure level [2], the type of mating materials [3], the curing methodology [4], the operating temperature [5,6], the loading type [7] and the assembly procedure. [8]