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Power Screws, Fasteners, and Connections
Published in Ansel C. Ugural, Mechanical Engineering Design, 2022
It should be pointed out that the lap joints may be inexpensive because no preparation is required except, possibly, surface cleaning, while the machining of a scarf joint is impractical. The exact stress distribution depends on the thickness and elasticity of the joined members and adhesives. Stress concentration can arise because of the abrupt angles and changes in material properties. Load eccentricity is an important aspect in the state of stress of a single lap joint. In addition, often the residual stresses associated with the mismatch in the coefficient of thermal expansion between the adhesive and adherents may be significant [13,14].
Fundamentals of Linear Elastic Fracture Mechanics
Published in Cameron Coates, Valmiki Sooklal, Modern Applied Fracture Mechanics, 2022
Cameron Coates, Valmiki Sooklal
Consider a plate subjected to stress as shown in Figure 2.2. Holes within any geometry result in a diminished area of material available for the cross-section. The lines of stress are therefore more concentrated within the smaller cross-section. The local stress will be some multiple of the remote stress. This multiplying factor is called the stress concentration factor, which is dependent on geometry only. Stress concentration occurs for any geometrical reduction of cross-sectional area; therefore notches, grooves, and fillets all result in stress concentrations as well.
Shaft Design
Published in Wei Tong, Mechanical Design and Manufacturing of Electric Motors, 2022
In order to quantitatively describe the phenomenon of stress concentration, a dimensionless factor, known as stress concentration factor K, is introduced as the ratio of the actual maximum stress with the stress riser to the nominal stress without the stress riser, that is, K=Actual maximum stressNominal stress
Non-conforming and conforming five-node quadrilateral graded finite elements
Published in Mechanics of Advanced Materials and Structures, 2023
This example addresses local stress concentration in which mesh refinement is recommended in the regions of high stress gradients. A 2D plate of size 10 × 10 is considered with top and right edges are constrained with the bottom-left corner node subject to a point load as shown in Figure 9a. The gradation of Young’s modulus along the diagonal direction is given by Eq. (26) in which x is replaced by x’. E1 and E2 are the moduli at left-bottom and top-right corners. Due to a point load, stress concentration will occur near the loaded point. Figure 9a depicts a graded plate subjected to point load P with linearly varying Young’s modulus of elasticity E along x’ direction. Figure 9b illustrates the arrangement of transition Q5 elements with Q4 and Q8 elements.
Effect of drilling-induced defects on progressive damage of open-hole composite laminates under compression
Published in Advanced Composite Materials, 2022
Abebaw Molla Endalew, Kyeongsik Woo, Douglas S. Cairns
Secondary machining processes such as drilling, milling and trimming are needed to achieve the dimensional tolerances and assembly specifications of composite laminate components. For example, in the aerospace industry, thousands of drilling operations are necessary to provide open holes for rivets and screws [2,3]. The presence of irregularities in the geometry of a structural element, such as holes, notches or changes in cross section, causes significant changes in stress distribution, known as stress concentration [4]. In reference [5] a single open hole caused a reduction of more than 40% in the compressive strength of T800/924C multidirectional laminate, and another study by reference [2] reported a 37.8% decrease in the compression strength of carbon fiber/epoxy composite laminates. Drilling of open holes in carbon fiber reinforced polymer (CFRP) composite laminates is very challenging and usually induces machining defects such as delamination, fiber pullout, uncut fiber (burrs), tearing, micro-cracking, matrix degradation and melting, among which delamination is the most crucial defect [6–10]. In addition to stress concentration, the presence of one or more of such defects can cause assembly fitting problems. In the aircraft industry, drilling-associated delamination is responsible for 60% of all rejections during the final assembly of an aircraft [11,12].
Impact response of a partially filled fuel tank subjected to high-velocity projectiles
Published in Australian Journal of Mechanical Engineering, 2022
Anurag Purbey, Rajeshkumar Selvaraj, Manoharan Ramamoorthy
The fillet is done on all the 12 edges of the tank with a radius varying from 10 mm to 30 mm with 5 mm increments. The stress concentration could be controlled by avoiding sharp corners in any structure. Mansooria and Zareib (2019) show that when shock waves are created when the bullet strikes the tank and these shock waves travel and expand the tank. In this expansion, stress is generated at corners above and below the point of contact. It is observed from Figure 6 that the stress at the corner below the point of impact creates more stress than at the top of the point of contact in Figure 7. This is due to shock waves created by water directly affecting the bottom and at the top, there is only air so the stress is comparatively low.