Preliminary design of a wing spar bonded joint

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Wing sparFast tools such as the ESAComp module for bonded joints can be very efficient in the preliminary design of various joint configurations. In this example we consider a tip loaded wing of a small aircraft or wind turbine blade. The wing spar carries a constant in-plane shear (Nxy), which needs to be transferred from the joint laminates to the shear web.

Adhesive stressesA parameterized double lap joint allows efficient examination of how the parameters of the joint (laminate selection, joint overlap length, selection of the adhesive material and the thickness of the joint) influence the performance of the joint. The joint can be loaded with a combination of in-plane tension/compression, in-plane shear, out-of-plane shear, and the bending moment. This example follows the study of the reference [1]. In-plane shear stress resultant induced out-of-plane shear stresses τyz have been studied for various overlap lengths (10/25/50mm). ESAComp results shown below are in-line with the ones presented in the reference.

Typical FE approach for modeling wing structures is based on shell elements. The study of the discontinuity needs special methodology and it is often neglected. From the FE solution, resultant forces and moments can be extracted and used as an input for the specific bonded joint analysis tools. This approach provides means to use the best suited solution for different phases of the design process.

ESAComp also allows going beyond the elastic limit of the adhesive. To learn more about this and various other details of the analysis module, see ESAComp Example Cases: Bonded Lap Joint

 

[1] Stress Analysis of In-Plane, Shear-Loaded, Adhesively Bonded Composite Joints and Assemblies, DOT/FAA/AR-01/7, April 2001