# Research on the Use of Hydro-Pneumatic Shock Absorbers for the Rear Suspension of a Vehicle Cabin
## 4 Results and Discussion
### Experimental Analysis Results on the Proposed Materials of the Air Socket
To ground the theoretical analysis in real-world application, two crucial cabin load scenarios are considered: an empty cabin with a defined force of 2400 N and a mass of 244.648318 kg, and a loaded cabin demanding a force of 8500 N and a mass of 866.4627931 kg. The longitudinal samples exhibit high ductility, demonstrating significant elongation before fracture (strains of 2.3-2.5), but with relatively low tensile strength, peaking around 9-10 MPa (Figure 11). Their initial stress-strain response shows a shallow slope, indicating low stiffness, and the curves suggest substantial plastic deformation before fracture. This behavior positions these samples as highly flexible materials, suitable for applications where extensibility and energy absorption are prioritized over high load-bearing capacity, with the reinforcing material having the least influence from all the samples. The transversal cut samples display a higher tensile strength, reaching peaks between 12 and 16 MPa (Figure 12), making them stronger than the longitudinal cut samples. While less ductile than the longitudinal samples (strains at break around 0.6-0.8), these samples still exhibit considerable elongation. Their initial stiffness is comparable to the previous samples, but many of the specimens show clearer signs of strain hardening, where the material gains strength as it deforms plastically before reaching failure. This suggests that the samples cut in a transversal direction offer a more balanced combination of strength and flexibility, with the reinforcing material of the rubber having more influence than in the previous case. Figure 11: Stress-strain distributions for longitudinal samples. The samples cut at 45 degrees exhibit significantly steeper initial slopes, indicating a higher stiffness, and achieve peak tensile strengths ranging from approximately 20 to 26 MPa (Figure 13). While their ductility is reduced compared with the previous two directions, as an influence of being cut near the direction of the inner reinforcing material, they still retain some elongation and show clear elastic and plastic deformation regions, often with strain hardening. The samples cut at 60 degrees represent the top tensile strength among all tested sample directions, reaching peak stresses from around 30 MPa to almost 50 MPa in some instances (Figure 14). This exceptional strength, however, comes with a trade-off as these samples display the lowest ductility, fracturing at strains typically between 0.3 and 0.45. Their stress-strain curves are characterized by very steep initial slopes and a more direct path to fracture after reaching ultimate strength, indicating a more brittle failure mode. In this case, we cut the sample in the direction of the reinforcing material, with the results being influenced by this factor. This shows that the reinforcement material increases the  
Figure 12: Stress–strain distributions for transversal samples. Figure 13: Stress–strain distributions for samples with a diagonal cut at 45\({}^{\circ}\). mechanical properties by up to 3.5 times compared with the samples cut in a longitudinal direction. The methodology's current application, as presented, is primarily analyzed for two main cases, an empty cabin and a loaded cabin, representing standard vehicle loads. The focus is on improving comfort and stability for typical road and engine vibrations. A key limitation regarding the behavior and characteristics is the material itself. While capable of carrying a high load, the continuous exposure to forces significantly beyond standard vehicle operations can push the system's components, including the reinforced rubber air chamber, to their material limits, potentially accelerating wear and failure (e.g., due to weak interfacial adhesion between fibers and rubber as noted in the previous chapters). This material characteristic could significantly impact the air chamber's durability and performance when subjected to severe and continuous impacts, heavy loads, and high-frequency oscillations.