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Joining and Repair
Published in P. K. Mallick, Processing of Polymer Matrix Composites, 2017
The joint design parameters are usually determined by conducting pin-bearing tests. In pin-bearing tests, a pin is inserted through the hole at one end of the composite, which is then loaded in tension until failure at the hole occurs (Figure 11.5). It is observed in these tests that the pin-bearing strength increases with both e/d and w/d ratios (Figure 11.6). Shear-out occurs at low e/d ratios and bearing failure occurs at high e/d ratios. Similarly, net tension failure occurs at low w/d ratios and bearing failure occurs at high w/d ratios. The e/d and w/d ratios, at which the failure mode changes from shear-out or net-tension failure to bearing damage, increase with increasing clamping torque. The use of a washer increases the joint strength, since it increases the clamping area and provides a lateral restraint. But it is observed that for a constant clamping torque, the joint strength decreases with increasing washer diameter, since it reduces the clamping pressure. Washers with sharp edges should not be used since they can create damage in the surface of the composite part.
Joining processes (mechanical connections)
Published in Roger Timings, Fabrication and Welding Engineering, 2008
In addition to the commonly used ‘plain’ or ‘flat’ washer, various other types are used; for example, the taper washer and the spring washer. Taper washers are used to ensure that the contact surface of the bolt head and nut are square with the axis of the hole so that the bolt is not bent and weakened. They are available with a 5° taper for use on the inside of joist or channel flanges, and with an 8° taper for use on the inside of ‘T’ section flanges.
A computationally efficient methodology to simulate hybrid bolted joints including thermal effects
Published in Mechanics of Advanced Materials and Structures, 2021
José M. Guerrero, Aravind Sasikumar, Jordi Llobet, Josep Costa
The material properties can be found in Table 1. The bolt, washer and nut are made of steel. All materials are assumed linear elastic and CFRP is considered orthotropic, with 40 plies. The coefficient of thermal expansion, CTE, is considered isotropic for metals and is given in the three directions for CFRP. The laminate stacking sequence is defined in ABAQUS using the ‘composite layup’ feature [40]. Three integration points are considered for each ply of the laminate. All contact interfaces have a friction coefficient of 0.315, as determined experimentally. Moreover, for the CONVS model, a tie constraint holds the plates and doublers together. In contrast, the 3D solids and CONTS models do not need this tie constraint since the plate and doubler are modeled as a single part. We omitted the weight of the assembly.
Large thermal hysteresis NiTi Belleville washer fabricated by metal injection moulding
Published in Powder Metallurgy, 2020
Wenbo Li, Hao He, Dongyang Li, Yimin Li, Jia Lou, Zheyu He, Yongzhi Chen, Yi Xie
At the beginning, common spring washer exhibited a similar temperature to that of the Belleville washer. However, after the loosening of the nut by 1/6 turn, the normal spring washer temperature was 82.3°C, while that of the Belleville washer was significantly lower, 44.1°C. After loosening by 2/6 turn, the spring washer temperature was 99.1°C, while that of the Belleville washer was only 43.9°C. The ordinary spring washers are also designed to use their elasticity and thermal expansion to tighten the loose nut. However, even if the bolt is loose only by 60°, the temperature in the line exceeds the critical temperature of 60°C specified by the power industry standard. In contrast, the NiTi alloy provides a more reliable restoring force through the phase transformation and thus exhibits a higher performance.
Asymmetric Friction Connection Bolt Lever Arm Effects on Hysteretic Behaviour
Published in Journal of Earthquake Engineering, 2022
Jose Christian Chanchi Golondrino, Gregory Anthony MacRae, James Geoffrey Chase, Geoffrey William Rodgers, George Charles Clifton
The 6 groups of 3 AFCs in Table 1 used 2 mm bolt hole oversize, shims of 6 mm thickness, structural washers of 4 mm thickness, flat washers of 4 mm thickness, and single Belleville washers beneath the nut with a thickness of 2.5 mm at the fully squashed condition. The bolt grip length measured outside of the structural and Belleville washers included the structural washer, the 3 Grade 300 steel plates, the 2 shims, the flat washer, and the fully squashed Belleville washer. The bolt lever arm, l, was assessed as the distance from the top shim-cap plate interface to the bottom shim-fixed plate interface, as shown in Fig. 2c (Khoo et al. 2014).