Архивы рубрики ‘Mechanical Properties,. Technologies and. Economic Importance’


From the two studies discussed above, it is clear that, in order to measure the entire profile of BFS along the backface of the bonded region, the use of an array of strain sensors is a feasible solution. It is also seen that, the use of an array of FBG sensors yields more accurate results […]


From the static investigations, as shown in Figure 10, it can be seen that the position of the negative peak of BFS distribution, determined by the experiments using arrays of strain gauges as well as FBGs, matched with the value obtained from FE analysis. In case of the use of electric strain gauge arrays, the […]

Experimental Investigation

A servo-hydraulic system from MTS Landmark™ Testing Solutions with a capacity of 100 kN was used, in an environment with controlled temperature and humidity. A static load was applied to the specimens with strain gauges and specimen with FBG array without any crack. Figure 9. (a) FE model with three lines to be analyzed for […]

FE Analysis

The BFS distribution was then investigated in FE analyses for the backface of aluminum substrate. A number of FE analyses were carried out by continuously varying the crack lengths in order to understand the behavior of BFS distribution during fatigue crack propagation. The strain values extracted from the FE analyses to construct the BFS profile […]

Metal-Composite Single Lap Joint

Specimen In this case, an aluminum-carbon fiber reinforced polymer (CFRP) adhesively bonded SLJ was investigated [46]. Woven CFRP adherent having 0° ply orientation was bonded with an aluminum adherend by epoxy structural adhesive DP 760. The detailed shape and dimensions of the specimen are given in Figure 8. Four specimens were manufactured. Two specimens were […]


A comparison between FE simulations and FBG measurements was made. The result is shown in Figure 7 for a crack length of 7 mm. The BFS distribution measured by an array of FBG sensors and interpolated by spline interpolation has a similar trend as the FEM results, as shown in Figure 7. Figure 7. BFS […]

Use of an Array of FBG Sensors

In order to capture the BFS distribution along the backface of the bonded region (as shown by red line in Figure 6), an array of FBG sensors is well suited to this purpose. An array of 10 FBG sensors, as shown in Figure 6, was used in this case in order to sense BFS distribution. […]

Finite Element (FE) Analysis

The full laminate was modeled in FE analysis using 2D solid elements with partitions having the properties of the corresponding plies. A thin layer of solid elements was inserted between the adherends, to simulate the presence of the adhesive layer. By gradually removing elements in the adhesive layer, the crack propagation was modeled. The variation […]

Case 1: Tapered Single Lap Joint

Specimen In the first case [28], a tapered lap joint was considered having two CFRP composite laminate thick bars as adherents. The shape and dimension of the specimen is given in Figure 1(a). Total thickness of the laminate is 10 mm. The laminate is made of woven (W) and unidirectional (UD) laminae of CF and […]

Case Studies on Backface Strain Technique. for Fatigue Crack Growth Monitoring

Adhesively bonded SLJs have been extensively studied by numerous researchers due to their simplicity and efficiency [47]. One feature associated to this joint configuration is the stress distribution (shear and peel) in the bondline, which is characterized by stress concentrations at the ends of the bondline. Under these conditions, fatigue crack nucleation at one or […]