PSI - Issue 25

Wojciech Danek et al. / Procedia Structural Integrity 25 (2020) 19–26 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

21

3

Fig. 1. The drop-weight impact test rig during impact loading of the specimen.

The initial condition was connected with the velocity of the impactor during testing, which was determined on the basis of the knowledge of its mass and the impact energy. The method of the support of the composite plate during the impact and its influence on the results of numerical simulations are presented in section 3.2. The parameters of the considered composite material such as Young modulus, Poisson ratio, or strength for both tensile and compression were determined based on experimental research presented in (Wronkowicz-Katunin et al., 2019). In the case of modeling the composite plate as 10 separate layers, which is consistent with the number of composite layers of the applied plate, the energy release rate (Mouritz, 2012) value was necessary and it was determined from the mode I interlaminar fracture tests on BCB specimens (see the details in (Wronkowicz-Katunin et al., 2019)). To simulate the composite material of the plate in LS-Dyna, the material model MAT_054 ENHANCED_COMPOSITE_DAMAGE was used. It is a model designed for calculations of orthotropic materials, such as, for instance, laminates reinforced in one direction or laminates reinforced with fabrics. This model takes the Chang/Chang failure criterion (Hallquist, 2006; Hallquist, 2007 ) into account. A list of parameters of the numerical model is shown in Table 1.

Table 1. A list of parameters of the numerical model Parameter

Value

Thickness of the composite plate Number of nodes*

2.5 mm 67775-280570

Number of brick elements

57444

Number of shell elements* Number of material models used

1320-211200 3

* Depends on the variant of the simulation

To compare the results obtained from different kinds of the numerical simulation the same scale was adopted. It was connected with the surface area that was damaged during the impact. This scale was chosen because of the planned comparison of the results of the numerical simulation with results obtained from experimental research.