Civil Engineering Reference
In-Depth Information
of the extra dimensions, which will cost extra funds to perform such operation,
but what is the solution in the case of curing of composite parts?. Water jets
cutting is used to adjust composite parts dimensions, but not simulated in this
chapter.
• Maintenance is very expensive, especially for satellite applications. Hidden
cracks that are initiated during manufacturing and may lead to structure failure
later during transportation or operation (Test case in
Chap. 6
).
Using nonlinear finite element method to simulate the manufacturing process can
help to optimize its design parameters and produce better parts. The main topics
discussed in this chapter are riveting, shot peening, and material removal. Riveting
is used to assembly, shot peening is used in metal forming or to improve fatigue,
while material removal is used for shaping or fixing imperfect part.
7.2 Electromagnetic Riveting Simulation
The LVER (low voltage electromagnetic riveter) machine uses an electrical energy
stored in capacitors, which is discharged through a magnet coil, accelerating an
armature that carries rivet die. A similar configuration is applied to both ends of
the rivet, to deform it and fix the assembly together. The electromagnetic rivet
upset process time is around 1-6 ms, where very fast plastic deformations lead to
significant localized heating of the rivet material and high strain rates around
10
3
s
-1
. The expansion of the rivet inside a fastener hole will create compressive
residual stress around the hole. Rivet joint quality is affected by many parameters:
sheet thickness, rivet diameter, rivet pitch, and squeeze force. However, the
squeeze force has the most significant role Muller [
1
]. Muller showed that using a
high squeeze riveting force can increase joint fatigue life up to 3 times. The
fastening process has been investigated experimentally and numerically by other
researchers [
2
-
8
]. Their work is focused mainly on how the geometrical and
manufacturing parameters of the process (squeeze force, rivet type, and plate
material) affect the induced residual stresses around the joint and the fatigue
performance of a single rivet specimen, but none investigated head_die design
effect on the residual stresses or the global panel deformations due to large number
of rivets used.
7.2.1 Finite Element Model
In this section, the riveting process is simulated by applying explicit finite element
analysis (ABAQUS) that includes coupled thermal stress equations, nonlinear
material properties, contacts, and large deformations. This model is used to model
the riveting process and predict stresses, deformations, and temperature as a
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