## 3 Results and Discussions
### Design Analysis and Finite Elements
The third proposed hollow design, shown in Figure 6c, is the evolution of the previous design with the removal of materials (where zero or little stress). One rib was added to the lower part of the control arm to increase the rigidity of the control arm in this critical region. The total mass of the structure was decreased to 1082 g; however, stress concentration regions are expected to occur near the hollowed regions, which may cause easier fracture. The formation of these stress concentration regions is due to the presence of holes in the web of the control arm. Therefore, a renovation of this design was needed that has the advantage of weight reduction without the use of pierced web. The solution of this  
Figure 7: Finite elements analysis (FEA) of inclined web design. (**a**) von Mises stress plot, (**b**) total displacement plot, (**c**) cross-sectional stress distribution. problem was found by the development of the succeeding design. The finite elements analysis (FEA) of the hollow design results are found in Figure 9. A maximum von Mises stress of 287 MPa is observed above the location of the lower bushing, higher than the two previous designs. The maximum SCF decreased significantly to 5.2 despite the very high stress. The maximum deformation is observed to be 1.69 mm, which is higher than all other previous designs. The high deformation and low SCF signifies that the stress is more homogenously distributed on the whole part. High stresses are observed near the locations of the holes marked with red arrows. The trussed design was developed to solve the issue of stress concentration due to web piercing; thus, this design replaced the middle web with a number of ribs as shown in Figure 6d. Regarding this design, five ribs were developed to withstand the loading conditions and to connect the upper and lower flanges of the control arm. The idea of the design is to increase the flexibility of the control arm structure; thus, ensuring that the stress is distributed evenly throughout the whole part. The shape, number, dimensions, and locations of the ribs were selected, after multiple trial and errors, to compromise the weight and performance of the part. The trussed design is the lightest design, weighing only 1040 gm, making it the most efficient design in terms of weight. The design resembles  
Figure 8: FEA of planar thin web design; (**a**) von Mises stress plot, (**b**) total displacement plot, (**c**) cross-sectional stress distribution. Figure 9: FEA of hollow design; (**a**) von Mises stress plot, (**b**) total displacement plot, (**c**) other view of Von Mises (VM) stress plot. the shape of trusses found in many structures as bridges and steel buildings; hence, where its name comes from. The idea of the design is based on removing excess material and distributing loads on the whole structure of the control arm rather than the concentration of stress in particular regions and zero stress in others. The maximum von Mises stress of the trussed design is shown in Figure 10a is 198 MPa. A remarkable maximum SCF of 2.475 is observed, indicating a complete homogenous distribution of stress over the whole body of the control arm. A maximum displacement of 1.78 mm is found at the location of the ball joint. The maximum stress location is shifted from the previous designs and located near the location of the arrows. The design is less rigid than other designs and transfers the force evenly throughout the whole part. Figure 11 shows a summary of the results of the four designs compared to the original design. The trussed design is observed to have the lowest maximum Von Mises (VM) stress and the lightest weight. Percentages of enhancement is calculated and colored for the ease of comparison between different designs. Percentages were calculated by using the relation as follows:  
\[\text{Percentage of enhancement}=\text{(original value-new value)}\ /\ \text{(Original value)}\times 100\]  
Another study applied by [PERSON] et al.