Manufacturing Simulation Using Finite Element - Finite Element Analysis for Satellite Structures - page 273

Fig. 7.6 Meshed FE model of riveting process

Table 7.1 Material mechanical properties of panel
Material type Aluminum 2017-T4

Johnson-Cook parameters A = 369 MPa—B = 684 MPa

n = 0.73—m = 1.7
C = 0.0083—e o = 1

T melt = 775 K

conductance, the work of Yuncu [ 9 ] is used here to estimate the value of
contact conductance.

• The model is meshed with hexagonal elements, as they are more suitable for
material forming simulations; meshed model is shown in Fig. 7.6 .
• The rivet is meshed with elements of size (0.25 mm), while the panel and
stiffener volumes near the rivet are meshed with elements of size (0.5 mm).
• The material models used for the nonlinear finite element analysis replicate the
effect of the heat generated due to high strain rate on the resultant residual
stresses. As a result, a Johnson-Cook plasticity model is used in order to
describe the nonlinear behavior of the panel, stiffener, and rivet material.
Johnson-Cook hardening is a particular type of isotropic hardening, where the
static yield stress is assumed to be of the form

m

_

r ¼ A þ B e pl n

1 þ C ln

e pl
e 0

T
T melt

1 ð 7 : 1 Þ

where e pl is the equivalent plastic strain and A, B,C,e 0 , n, and m are material
parameters measured at or below the transition temperature (T trans = 25 C). The
Johnson-Cook material parameters of the panels are listed in Table 7.1 . Inelastic