• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.8
• /
• pp.1980-2000
• /
• 1993

The stresses and torque transmission capabilities of adhesively bonded circular, hexagonal and elliptical lap joints were analyzed by the finite element and compared with the experimental results. The adherends of the joints were composed of carbon fiber/epoxy composite shafts and steel shafts. In calculating the torque transmission capabilities, the linear laminate properties of the composite material and the nonlinear shear properties of the adhesive were used. Using this method, the torque transmission capabilities of adhesively bonded lap joints could be obtained within 10% error compared to the experimental results except some single lap joints. The experiments revealed that the hexagonal joint had the best torque transmission capability from the single lap joints and the double lap joint had better torque transmission than the single lap joint.

• Journal of Aerospace System Engineering
• /
• v.17 no.2
• /
• pp.62-70
• /
• 2023

We proposed a technique for predicting Stress-Life (S-N) curve or fatigue life using geometric features of a ply-overlap joint structure in which plies of two composite materials are partially or wholly laminated and bonded. Geometric features that could affect fatigue properties of a structure were selected as variables. By analyzing relationships between geometric variables and material constants of the Epaarachchi-Clausen model, a fatigue model for composites, relational expressions of these two factors were proposed. To verify the prediction accuracy of the proposed method, fatigue life of a CFRP/GFRP ply-overlap joint was predicted. Predicted life and life obtained by test data-based model were compared to actual life. High prediction accuracy was confirmed by calculating the coefficient of determination of the predicted S-N curve.

• Proceedings of the KSME Conference
• /
• 2001.06b
• /
• pp.624-629
• /
• 2001

Two types of bolted lap joints, one with a viscoelastic layer and the other without the viscoelastic layer were chosen to analyze the dynamic characteristics of the joints with the mechanical properties of the bolts of the joints being taken as computational variables. The finite element method was used along with the impact hammer technique to verify the FEM model. The results in the bolted lap joints reveal that the higher the Young's Modulus for the bolts are the higher the natural frequencies results for the joints. However, the natural frequency differences in the first and second mode are not substantial but become noticeable in the higher modes. Lower natural frequencies were obtained for the bolted lap joints with the viscoelastic layer when compared with those of the bolted lap joints without the viscoelastic layer. And the differences in the natural frequencies for the two types of joints are relatively small in the first and second mode whereas in the higher mode the differences become significant. The loss factors were observed to be significant especially in the second mode for the bolted lap joints with the viscoelastic layer.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.1
• /
• pp.172-178
• /
• 2003

Two types of bolted lap joints, one with a viscoelastic layer and the other without the viscoelastic layer were chosen to analyze the dynamic characteristics of the joints with the mechanical properties of the bolts in the joints are considered as computational variables. The finite element method was used along with the modal testing to verify the PEM model. The results in the bolted lap joints reveal that the higher the Young's modulus for the bolts we use the higher the natural frequencies we obtain fur the joints. However, the natural frequency differences in the first and second mode are not substantial but become noticeable in the higher modes. Lower natural frequencies were obtained for the bolted lap joints with the viscoelastic layer when compared with those of the bolted lap joints without the viscoelastic layer. And the differences in the natural frequencies for the two types of joints are relatively small in the first and second mode whereas in the higher mode the differences become significant. The loss factors were observed to be significant especially in the second mode for the bolted lap joints with the viscoelastic layer.

• Journal of the Korean Society for Precision Engineering
• /
• v.32 no.11
• /
• pp.929-935
• /
• 2015

The long neck flange is used to connect piping arrangements where the lap joint is applied. Generally, the component can be manufactured by welding, but this method is both time and cost intensive. Embrittlement at the heat affected zones was also considered. A spinning method developed to improve the manufacturing process and solve the problems of welding. The flange area of the long neck flange can be formed by changing the direction of the metal flow, from axial to radial, while maintaining pressure by using an outer mold and a lap roller. A modified process was additionally developed using a round roller rather than the outer mold. In this modification, the round roller can form the shape of all sizes of long neck flange. Using these flexible methodologies, the cost to prepare outer molds and the time to install and remove the molds can be significantly reduced.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.3
• /
• pp.319-325
• /
• 2015

High-strength steel has replaced mild steel as the material of choice for truck decks or frames, owing to the growing demand for lightweight vehicles. Although studies on the weld fatigue characteristics of mild steel are available, studies on high-strength steels have been seldom conducted. In this study, firstly, we surveyed a chosen number of approaches and selected the Radaj method, which uses the notch factor approach, as the one suitable for evaluating the fatigue life of commercial vehicles. Secondly, we obtained the S-N curves of HARDOX and ATOS60 steel welds, and the F-N curves of the T-weld and overlapped-weld structures. Thirdly, we acquired a general S-N curve of welded structures made of high-strength steel from the F-N curve, using the notch factor approach. Fourthly, we extracted the weld fatigue characteristics of high-strength steel and incorporated the results in the database of a commercial fatigue program. Finally, we compared the results of the fatigue test and the CAE prediction of the example case, which demonstrated sufficiently good agreement.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.36 no.1
• /
• pp.57-65
• /
• 2023

A vibration response-based detection system was used to investigate the adhesive areas of single-lap joints using a nonlinear transformation approach for deep learning. In industry or engineering fields, it is difficult to know the condition of an invisible part within a structure that cannot easily be disassembled and the conditions of adhesive areas of adhesively bonded structures. To address these issues, a detection method was devised that uses nonlinear transformation to determine the adhesive areas of various single-lap-jointed specimens from the vibration response of the reference specimen. In this study, a frequency response function with nonlinear transformation was employed to identify the vibration characteristics, and a virtual spectrogram was used for classification in convolutional neural network based deep learning. Moreover, a vibration experiment, an analytical solution, and a finite-element analysis were performed to verify the developed method with aluminum, carbon fiber composite, and ultra-high-molecular-weight polyethylene specimens.