Faruk Sen

The Effect of Preload on Failure Response of Glass-Epoxy Laminated Composite Bolted-Joints with Clearance:

In this study, the effect of preload moments on failure response of glass-epoxy laminated composite bolted-joints with bolt/hole clearance was investigated. To evaluate the effects of bolted-joint geometry and stacking sequence of laminated plates on the bearing strength and failure mode, parametric analyses were performed, experimentally. Two different geometrical parameters, edge distance-to-hole diameter ratio (E/D) and plate width-to-hole diameter ratio (W/D), were examined. For this reason, the E/D ratio was selected from 1 to 5, whereas the W/D ratio was chosen from 2 to 5. Besides, preload moments were applied as 0, 3 and 6 Nm. Due to the estimating material parameters effect, laminated plates were oriented as three different groups, [0°/0°/90°/90°]s, [45°/45°/—45°/—45°]s and [60°/60°/—60°/—60°]s, symmetrically. The experiments were also performed under a clearance for the diameters of the bolt and the circular hole for 5 and 6 mm, respectively. Experimental results showed that failure mode and bearing strength are strictly affected by the magnitude of preload moments. Additionally, if material and geometrical parameters of composite bolted-joints are changed, the failure response is completely influenced by this change.

Experimental determination of bearing strength in fiber reinforced laminated composite bolted joints under preload

In this study, a failure analysis was carried out to determine bearing strengths of mechanically fastened joints with single bolt in glass—epoxy laminated composite plates. Two different geometrical parameters that were the edge distance-to-hole diameter ratio (E/D) and plate width-to-hole diameter ratio (W/D) were investigated. For that reason, E/D ratio was selected from 1 to 5, whereas W/D ratio was chosen from 2 to 5. Tensile tests were subjected to composite bolted joints for four different ply orientations such as angle-ply [0/30]s, [0/45]s, [0/60]s, and cross-ply [0/90]s. The major focus of this study was to observe the failure mechanisms of bolted joints under various preload moments as 0, 2.5, and 5 Nm. The experimental results showed that the magnitudes of bearing strengths in bolted joints were strictly influenced from increasing value of applied preload moments, changing of W/D and E/D ratios, and also ply orientations of laminated composite plates.

Failure Analysis of Laminated Composite Plates with Two Parallel Pin-loaded Holes

The aim of this study is to research the failure loads and failure modes of laminated woven-glass—polyester composite plates with two parallel circular holes, which are subjected to traction forces by two rigid pins. The failure behavior of two parallel pin-loaded composite plates has been observed both experimentally and numerically with different geometries and fiber orientations. While the plate width to hole diameter ratio (W/D) was held constant; the distance from the free edge of the plate to hole diameter ratio (E/D) was changed from 1 to 5, and the distance between two parallel holes to hole diameter ratio (M/D) was varied from 2 to 5. Two different ply rientations were also investigated as [0°]8 and [0°2=60° 2/]s. In a numerical study, a three-dimensional finite element method (FEM) was used with the assistance of a LUSAS 13.6 finite element analysis program. Good agreement has been shown between experimental and numerical results.

AN INVESTIGATION OF SQUARE DELAMINATION EFFECTS ON THE BUCKLING BEHAVIOR OF LAMINATED COMPOSITE PLATES WITH A SQUARE HOLE BY USING THREE-DIMENSIONAL FEM ANALYSIS

In the present study, the effects of the square delamination, around a square hole, on the buckling loads of the simply supported and clamped woven steel-reinforced thermoplastic (LDPE, F.2.12) laminated composite plates have been investigated. Three-dimensional finite element models of laminated plates with four layers have been established. The square delaminations exist between second/third layers. The stacking sequences are chosen as [0]4, [15 / 15]s, [15 / 15]2, [30 / 30]s, [30 / 30]2, [45]4. Firstly the harmony between theoretical and finite element solution results of the plate without hole and delamination has been shown. Then, the buckling loads have been determined for each of the models having different square delamination dimensions. Significant decreases in the buckling loads occur after a certain value of delamination dimension. It is seen, for clamped plates that the changing ratios of the results of the symmetric or antisymmetric cases are approximately the same and there is a linear relationship between the values of the fiber angles and buckling loads.

Failure Response of Two Serial Bolted Aluminum Sandwich Composite Plates

The scope of this study is to examine the failure response in an aluminum—glass—epoxy sandwich composite plate with two serial circular holes, which is subjected to a traction force by two serial bolts. To determine the effects of joint geometry and applied/without preload moments on the bearing strength and failure mode, parametric studies were carried out experimentally. The end distance to diameter (E/D) and width to diameter (W/D) ratios in the specimens were designed from 1—5 to 2—5, respectively, whereas the distance between two serial holes and diameter ratio were fixed as 4. Besides, each type of specimen were tested under various applied preload moments as 2, 3, 4, 5 Nm and without preload moments (0 Nm). According to the experimental results, the bearing strength and maximum failure load generally increase by increasing E/D and W/D ratios and of applied preload moments. Besides, failure modes strictly affected these parameters.

Experimental Failure Analysis of Glass-Epoxy Laminated Composite Bolted-Joints with Clearance Under Preload

In this study, a failure analysis of glass-epoxy laminated composite bolted-joints with bolt/hole clearance under various torques was carried out. To estimate the effects of joint geometry and fiber orientation on the failure strength and failure mode, parametric studies were conducted experimentally. The two different geometrical parameters were the edge distance-to-hole diameter ratio (E/D) and plate width-to-hole diameter ratio (W/D), E/D ratio was selected from 1 to 5, and W/D ratio was chosen from 2 to 5. The bolt preload torque was also carried out as 0, 3, and 6 Nm. To investigate the material parameters effect, laminated plates were oriented as three different stacking sequences [90o]8, [45o]8, and [0o] 8. The experiments were carried out with a clearance between the diameters of the bolt and the circular hole of 5 and 6 mm, respectively. According to experimental results, failure mode and bearing strength are strongly influenced by both material parameters and geometrical parameters. Additionally, when a torque is applied to the bolted-joints, the failure mechanism is affected by its increasing values.

Prediction of Bearing Strength of Two Serial Pinned/Bolted Composite Joints using Artificial Neural Networks

The aim of this study is to investigate the improvement of an artificial neural network (ANN) method for the prediction of bearing strength of two serial pinned/bolted E-glass reinforced epoxy composite joints. The experimental data from the previous study with different geometrical parameters without torque and various applied torque were used for developing the ANN model. Comparisons of ANN results with desired values showed that there is a good agreement between input and output variables of the experimental data. Therefore, ANN was illustrated to be a valid powerful tool for the prediction of bearing strength of two serial pinned/bolted composite joints.

Elastic-plastic thermal stress analysis in a thermoplastic composite disc applied linear temperature loads via FEM

The aim of this study is to obtain thermal stresses in a thermoplastic composite disc unidirectionally reinforced by steel fibers. Finite element method was used to calculate the thermal elastic and elastic-plastic stress distributions within the composite disc. Therefore, the solution was carried out using the ANSYS software. The temperature loading was chosen so as to vary linearly from inner surface to outer surface along the radial sections of the disc. Linear thermal loads were selected as to differ from each other. They were also adjusted from 90 to 130^oC. Thermal stresses were formed within the disc by the linear temperature loads due to its having different thermal expansion coefficients in radial and tangential directions. In line with the thermal analysis results, the magnitudes of the tangential stress components for both elastic and elastic-plastic solutions were above the radial stress components. In addition, the residual stress components were also calculated using both elastic and elastic-plastic solution results. The results obtained pointed out that the magnitudes and distributions of the thermal stresses and residual stresses were greatly influenced by the increase in linear temperature loads.

Estimation of Elastoplastic Thermal and Residual Stresses in a Thermoplastic Composite Disc Under Uniform Temperature Effect

In this study, an elastoplastic thermal stress analysis has been carried out on a thermoplastic composite disc that is unidirectionally reinforced by steel fibers. The finite element method (FEM) was used to compute thermal elastic and elastoplastic stress distributions in the model of the composite disc. The solution is performed using the ANSYS program. In order to evaluate the effects of uniform temperature, different temperature loadings are applied to the disc model uniformly. Both radial and tangential stresses are calculated under a uniform temperature loading which is chosen from between 80 to 120 C. Due to the composite disc having different thermal expansions in radial and tangential directions, thermal stresses were calculated by applying uniform temperature loading. The magnitude of tangential stress components for both elastic and elastoplastic solutions is higher than that of radial stress components. Moreover, residual stress components are obtained using the results of elastic and elastoplastic solutions. The calculated results point out that distributions and values of improved thermal stresses and residual stresses are considerably influenced with increasing uniform temperature loading.

Thermo-elastic Stress Analysis of Injection Molding Short Glass Fiber Filled Polymer Composite Disc with Holes

The aim of this study was to find out the influences of uniform thermal loads on a composite disc having many pin/bolt holes. Polymer composite disc reinforced short glass fibers were successfully produced by using injection and compression molding techniques, and microstructural observations were carried out using an electronic microscope. A thermo-elastic stress analysis was performed utilizing a finite element method (FEM). For this reason, the thermal stresses were determined by using ANSYS software package. The circular holes were created in the disc because of observing these effects on thermal stresses. The thermal loads were applied to the disc at a uniform distribution. Due to the composite disc having different thermal expansions in radial and tangential directions, thermal stresses were created in it by applied uniform thermal loads. The magnitude of the tangential stress components was higher than the radial stress components. The magnitudes and distributions of thermal stresses on the composite disc were considerably affected by increasing the uniform temperature loads and the presence of pin/bolt holes.