Failure Response of Two Serial Bolted Joints in Composite Laminates

Abstract

In this study, the failure response of two serial bolted joints in composite laminates was investigated. The composite material was consisted of epoxy matrix and glass fibers. To find out the effects of joint geometry and stacking sequences on the failure response, parametric studies were performed experimentally. Three different geometrical parameters that were the edge distance-to-hole diameter ratio (E/D), plate width-to-hole diameter ratio (W/D) and the distance between two serial holes-to-hole diameter ratio (K/D) were investigated. Hence, E/D, W/D and K/D ratios were considered from 1 to 5, 2 to 5 and 3 to 5, respectively. In addition, the failure tests were carried out for a range of preload moments as 2, 3, 4, 5 Nm and without any preload moments as 0Nm. Tested composite laminates were oriented two different stacking sequences as [0]8 and [0/0/90/90] s . Experimental results point out that failure response of two serial bolted composite joints are firmly effected from material parameters, geometrical parameters and the magnitudes of applied preload moments.

Low temperature and tightening torque effects on the failure response of bolted glass fiber/epoxy composite joints

“…The maximum shear stress ( τ ) occurred in fastener bolts while transmitting the load ( F ) just before the final failure occurred is calculated as follows where D s is the basic minor diameter of M6 bolts, n s the number of laps (sliding surface), and n f the number of bolts. As observed, the shear stress in bolts ( τ = 406.18 N/mm 2 ) do not exceed the shear strength ( τ max = 480 N/mm 2 ) of material even under the maximum failure load reached during experiments. On the other hand, because the specimen thicknesses (2 mm) are tolerably lower than the bolt diameter, the tensile stresses, originated from the bending moment can be neglected.…”

“…According to the joint geometry and the loading direction it can be obviously said that, the fasteners are mainly exposed to the effects of shear stresses in the experiments. It is well-known that, the allowable tensile strength of 8.8 grade bolt material is σ max = 800 N/mm 2 . The shear strength is τ max = 480 N/mm 2 , which is about 0.6 times the tensile strength.…”

“…It is well-known that, the allowable tensile strength of 8.8 grade bolt material is σ max = 800 N/mm 2 . The shear strength is τ max = 480 N/mm 2 , which is about 0.6 times the tensile strength. The maximum shear stress ( τ ) occurred in fastener bolts while transmitting the load ( F ) just before the final failure occurred is calculated as follows where D s is the basic minor diameter of M6 bolts, n s the number of laps (sliding surface), and n f the number of bolts.…”

“…In this study, vacuum-assisted resin infusion technique was used to produce the glass fiber/epoxy composite plate. The glass fiber layers with a density of 300 g/m 2 was laid on to the heater table according to specified orientations, [0/90/45/−45]s. After preparing the vacuum bag, a calculated amount of mixture composed of Duratek DTE 1000 resin and Duratek DTS 1100 fast hardener was prepared and drawn into the component by vacuum. The infusion process was carried on until complete impregnation.…”

“…An experimental study was conducted by Sen and Sayman, 2 to investigate the effects of joint geometry and stacking sequences on the failure response of bolted joints in composite glass fiber reinforced laminates. The results indicated that the geometrical and material parameters, namely the edge distance-to-hole diameter ratio ( E / D ), plate width-to-hole diameter ratio ( W / D ), the distance between two serial holes-to-diameter ratio ( K / D ), and stacking sequences, are firmly effective on failure behaviors.…”