MECH 3900 Coursework 1
Example report
1. Method
Four models will be generated, building from a simple theoretical approximation which assumed that the structure is a uniform cross section, uniformily loaded cantilever beam, through to a three-dimensional model which describes some of the geometric features in detail and allows the stress field to be visualised. Planned comparisons are listed in Table 1 and are designed to provide confidence in the final results of the plate model.
The maximum von Mises stress in the plate model will be compared to the yield stress of the aviation aluminimum to make an assessment of the chances of material failure. A maximum stress which is 20% below the material yield stress will be considered to indicate that the stabiliser is “fit for purpose” under the flight conditions tested.
Table 1: Models, measurements and planned comparisons.
Model Outputs / measurements Comparisons with other models
Theoretical Tip deflection and maximum stress. It is expected that the theoretical and simple beam res
ults will be the same. This comparison is to ensure that there are no mistakes in the basic calculations. The ball-park deflection and stress found here can be used as a sanity check for the more complex models.
Simple beam Tip deflection and maximum stress.
Complex beam Tip deflection and maximum stress. The complex model would not be expected to produce the same results as the simple model.
The deflection of this representation may be in between the simple model and the plate model, depending on the choices made.
Plate model Tip deflection, measured at the nose of the profile.
Deflection and strain fields.
Maximum stress, anywhere in the stabiliser, excluding the first layer of elements next to the boundary conditions. It is expected that the deflection will be in the same range as for the complex beam.
The strain field will be used to observe the overall deformation of the structure and check that this is sensible.
The stress field is much more sophisticated and therefore may not be directly comparable to any of the other models.