PSI - Issue 52

3

Author name / Structural Integrity Procedia 00 (2019) 000 – 000

Valerio Acanfora et al. / Procedia Structural Integrity 52 (2024) 340–347

342

Figure 1: Basic numerical model (on the left); model with guiding pins and fixture base (on the right).

Impact force and displacement values against time have been registered during the entire 5 ms duration of the impact, resulting in the force and displacement histories shown in Figure 2.

Figure 2: Experimental curves.

3. Numerical models Analyses have been conducted to develop a method which could potentially ascertain the complete range of in plane deterioration of the composite plate, from the unaltered material with no damage to the fully damaged material. The evolution of numerical models have been established using a step-by-step methodology. The initial phase entailed the definition of an effective numerical model able to simulate the impact event on the composite specimen without taking into account any failure, thus assuming an elastic behavior of the composite material. The initial model comprised of two components only: the specimen and the impactor, as shown in Figure 1. Subsequently, the guiding pins and the fixture were incorporated into the assembly. The other numerical models have been implemented by increasing the complexity through three main numerical parameters: element size in specimen mesh, number of elements in the specimen thickness, and element properties in pins for hourglass control. Four discretization levels through the thickness (1, 2, 4, and 8 elements) and three in-plane discretization levels (2.0, 1.5, and 1.0 mm) have been taken into account. Graphs for each in plane mesh size are not included in this work as they do not provide any significant information. It is evident that an increasing number of elements in the specimen thickness leads to a progressive reduction of the maximum impact force, in addition to an increase in terms of contact duration. Models with few elements through the thickness tend to overestimate the stiffness, thus the contact duration is shorter, and the maximum contact force is higher. Despite the fact that using a greater number of elements through the thickness increases the computational time significantly, this choice yields more precise results (Figure 3).