PSI - Issue 57

Sven Maier et al. / Procedia Structural Integrity 57 (2024) 731–742

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S. Maier et al. / Structural Integrity Procedia 00 (2023) 000±000

N s Number of independent variables p a ( σ a ) Probability density distribution of stress amplitudes P f Probability of failure T Total duration of load t m Thickness of mounting t p Thickness of plate t tp Thickness of thinner plate ϑ p

Expected rate of occurrence of peaks in a Gaussian process

Mean value

µ

Standard deviation Stress amplitude Modal damping

σ

σ a

ζ

2. Simulation model

2.1. Model description

The mass force excited component investigated in this study consists of a control unit device which is fixed via screws at a mounting frame which is attached to thins plates by means of stud weld bolts. The thin plates represent the body-in-white structure and the corners are clamped between a steel frame and aluminium rack. The steel frame is screwed with several screws through the thin plates to the aluminium rack to realise the clamping. To allow an oscillation of the system the middle of the aluminium rack is cut-out (areas behind the green plates). The finite-element simulation model is illustrated in Figure 1. The linear model is build up with the aid of the commercial software MSC Nastran. The control unit is modeled as concentrated mass (CONM) with equivalent values for the mass and mass moments of inertia and connected to the mounting with rigid body element, form 2 (RBE2) constraints. The stud weld bolts are realised by means of RBE2s, simple beam element connection (CBAR) and FemFat spots from the commercial software FemFat. The screws for fixing the frame to rack through the plates are realised by a combination of RBE2s and CBARs. To implement the fixture of the entire system, the screws in the aluminium rack are rigidly connected to a master node using RBE2 constraints, which block all degrees of freedom and also serves as an excitation point for vibration analysis. The simulation model consists of a total of 212071 shell and volume elements and 85050 nodes.

Fig. 1. Finite-element simulation model.