PSI - Issue 51

Daniel Ivaničić et al. / Procedia Structural Integrity 51 (2023) 199 – 205 D. Ivani č i ć et al. / Structural Integrity Procedia 00 (2019) 000–000

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deflection on central part of the beam is calculated and inserted in Eq. (1) which resulted in Young’s moduli of ABS and PET-G material, 2347,37 MPa and 2160,5 MPa respectively. Obtained results show good agreement with values found in literature, MatWeb (2020), and Autodesk Inventor’s materials database, as seen in Table 1. Experimentally obtained values were then used as input parameters in FE analysis.

Table 1. Young’s modulus of PET-G and ABS.

Young’s modulus, E [MPa] Values from catalogue, MatWeb (2020)

Material

Experimental value

Autodesk Inventor

ABS

2347,37 2160,5

1500 – 2600 2010 – 2110

2240 N/A

PET-G

2.3. Topology optimization of the load-bearing element Topology optimization was performed using Autodesk Inventor software, i.e. Stress Analysis module. The goal of the topology optimization of the initial volume, i.e. initial size and shape of the cantilever load-bearing element (Fig. 4. (a)), was the reduction of the overall mass while maintaining the load-bearing capability.

a)

b)

Fig. 4. (a) Initial volume of the cantilever plate load-bearing element with boundary conditions; (b) Meshed model with boundary conditions.

As was mentioned in subsection 2.2, for successful FE analysis, material parameters have to be assigned properly. PET-G material that will be used, along with ABS, for 3D printing of the optimized cantilever sample, is not available in Autodesk Inventor so its parameters ought to be determined. Yield stress R e and Poisson number ν are taken from the literature, MatWeb (2020). The Young’s modulus E is experimentally determined as explained in subsection 2.2. Since R e is given in range, the lowest value of 24 MPa is adopted to obtain conservative calculations. Further step is to exclude the areas for which the optimization will not be performed. Here that are the clamping and the loading area, as marked green in Fig. 4. (a). Clamping of the cantilever plate is set on the rectangular part with two holes that corresponds with clamping that will be obtained on the real sample. Loading force in vertical direction is set on the hole on the free end of the cantilever plate, as shown in Fig. 4. (a). Topology optimization depends on mesh density that depends on finite element size. These should be optimized in order to obtain the best ratio of details and analysis duration. Average and minimal element size are set to 0,01, mesh resolution is set to 1.00, while the percentage of the removed volume is set to 50 %. In Fig. 4. (b) the meshed model is shown, while Fig. 5. (a) represents the optimized shape obtained for the given parameters and boundary conditions. Based on the obtained results, parametric 3D model is made in Autodesk Inventor, Fig. 5. (b). In following sections it will be seen that the free end of cantilever load-bearing element, where the maximum deflection is expected, was redesigned when compared to optimization results to a rectangular-like shape in order to allow better raster application and easier recognition and definition of facets with GOM Correlate software used for processing of the experimental measurements using DIC. Optimized sample volume was reduced by 50,5 % when compared to initial volume resulting in mass reduction of 13,46 g (initial mass 27,081 g, end weight 13,261 g).