0 5 10 15 20 25 30 0.0 0.5 1.0 1.5 2.0 2.5 Experiment FE‐Prediction 3. Displacement (mm) Total Applied Load (kN) 0 0 5 10 15 20 25 30 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Displacement (mm) Total Applied Load (kN) FE‐ Prediction Experiment Fig. 14 Load–displacement behavior: Experimental (blue) and FE predictions (red) for model-1 (left) and model-2 (right). Additional validation of the FE model was performed by comparing the strains in the transverse direction at the location as of the experimental strain gages. The location of the strain gages are provided in Table 2. Fig. 15 compares the strain responses from FE model with experiments in the elastic regime for both T-stubs model. A slight discrepancy, in the form of a non-linear behavior in the experiment response was observed in model 1. It should be noted that the strain gages are placed in the vicinity of the bolt and the fillet-curvature which is a region of complex phenomena and is governed by many factors. Additional experimental tests and accurate FE modeling is required to quantify such phenomena. In general, good agreement in strain predictions of simulations with experiments was observed. 0 1 2 3 4 5 6 7 8 9 10 0 100 200 300 400 500 600 Strain ( ) Applied Load (kN) FE ‐ Prediction Experiment 0 1 2 3 4 5 6 7 8 9 10 0 50 100 150 200 250 300 350 Strains ( ) Applied Load (kN) FE‐Predictions Experiment Fig. 15 Comparison of strain at lateral surface from experiments (blue) and FE model (red) for model-1 (left) and model-2 (right) in the elastic regime. Overall, the validation of the FE modeling with experimental tests and DIC analysis revealed good agreement of FE models with experimental data. Nevertheless, statistically significant number of experimental tests and accurate modeling of the phenomena with detailed material properties are essential to further increase the confidence of the FE models and to establish the quantitative uncertainties and confidence limits for the numerical models. 7- Conclusions. 2D DIC has been used to study the complex strain field in a T-Stub joint. Good agreement between the results obtained for the displacement from T-surface using DIC and those obtained from an FE analysis reveals the utility of the latter in the study of real engineering problems. Further confirmation of the reliability of the FE model was achieved by using strain gages on the flange surfaces. The use of accurate material properties and the detailed modeling of complex interactions between the bolt-flange and flange-flange connections can further improve the FE model performance. The use of optical methods for stress and strain analysis, such DIC, is a great utility for validating finite element models. FE models developed with the confidence of experimental validation provide a valuable tool for optimizing dimensions or improving safety in complex problems, such T-Stub joints. 421
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