Stress state of an aircraft equipment structure with discrete welded connections at random kinematic loading

Аuthors

Rybaulin A. G.^*, Sidorenko A. S.^**

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

*e-mail: artcomj@gmail.com
**e-mail: k906@mai.ru

Abstract

Spot welding method is widely used in load-carrying structures of flight vehicles. An essential disadvantage of spot welding is the stress concentration higher than the concentration in similar rivet connections. To estimate the structures durability the local stress state near the welding point must be computed.
Some results of the mathematical of stress state of the load-carrying structures of aircrafts containing spot welded connections are presented. Stress state in the welding spots of the structures subjected to the random kinematic excitation is computed. The thin-walled cylindrical shell containing filling material that simulates the mass parameters of the structure are considered. The X-shaped wing and two attachment points are connected to the shell by means of spot welding. To simulate the dynamics of the considered structure with the discrete welded connections Solid Works software is used.
Welded points are simulated by allocation of adjacent circular areas on the wing and the shell with constrained relative displacement. Each welded spot is subdivided to 40 finite elements.
Dynamic computation of the structure is using the modal analysis for random processes. The dynamic stress state is defined for the kinematic loading by steady random acceleration. The spectral density of acceleration is set in a suspension point in the form of truncated «white noise».
As a result of simulation the distribution root-mean-square values of equivalent stresses in the structure points is obtained. The greatest level of stresses is observed in suspension points. The basic part of vibration stresses dispersion is located near the frequencies corresponding to natural modes of the structure.
Equivalent stresses fields along the seams are constructed. It is shown that the endpoints of seams are most loaded.

Keywords:

aircraft, welded connection, spot welding, wing box, shell, dynamic response, vibration acceleration, vibration stress, spectral density

References

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