## 3 Simulation and Experimental Results  
### Finite Elements Analysis of Suspension Rod  
Simulation results of Figure 8 indicate that for type A, peak stress at 1800 MPa (78.6% of yield stress) occurs at the rod body's inner arc near the metal washer, with stress diminishing outward. The CFRP rod deforms elastically and meets current load demands, but stress concentration suggests inefficiency in structural strength, implying potential for higher load capacity. In addition, Figure 8 analysis reveals that for type B, maximum stress of 2582 MPa occurs at the inner arc near the axle, exceeding CFRP's yield stress and causing delamination and damage. Stress concentration indicates inefficient strength use and further load increases could lead to failure. Type C shows tensile stress of 1600 MPa (69.8% of yield stress) with a slight concentration at the bolt root (79.5% of yield stress), still within usage limits. Type D has a maximum stress of 1950 MPa (85% yield strength) with a more uniform stress distribution, maximizing structural strength. Figure 9 compares axial load and deformation, showing types A and B have higher rigidity than types C and D. Type C, with a larger cross-section and one-piece design, is more rigid than type D. Finite element calculations indicate that type D, with the highest structural strength utilization rate and minimal material use, meets the axial tensile load requirements. Simulation results from Figure 8 analyze stress distribution and tensile deformation for four rod types. Type A experiences peak stress of 1800 MPa at the inner arc near the metal washer, which is 78.6% of the tensile yield stress, with stress diminishing outward. The CFRP rod deforms elastically, meeting load requirements, but stress concentration suggests inefficient strength use, indicating the potential for higher loads. Type B shows a maximum stress of 2582 MPa at the inner arc contacting the axle, exceeding CFRP's yield stress and causing delamination and damage. Stress concentration implies low structural efficiency and further load increases could lead to fracture. Type C has a tensile stress of 1600 MPa in the middle section, 69.8% of the yield stress, with a slight concentration at the bolt root (79.5% of yield stress), still within usage limits. The uniform stress distribution and higher structural strength utilization rate make it more efficient than Types A and B. Type D exhibits a maximum stress of 1950 MPa in the middle section, 85% of the yield strength, with forces distributed evenly across the rod, optimizing structural strength. Figure 9 compares axial load and deformation for the four types. Type A and B, with racetrack shapes, have higher rigidity than cylindrical structures. Type C, with a larger cross-section and one-piece design, has better rigidity than Type D due to closer fiber contact. Finite element calculations reveal that Type D, with the highest structural strength utilization rate, meets axial tensile load requirements using the least material, assuming equal material, rated load and axial effective length from the 300 K to 4 K end of the rod body. In Figure 9, although the cross-sectional area and length of the two are the same, the inner diameter of the arc section at both ends of the type A tie rod group is 50 mm, and it is equipped with A metal washer. The washer groove is refined to better fit the geometry of the arc section of the rod body to increase the contact area between the rod body and the metal part and can disperse the tension area well. At the same time, the larger circular diameter can reduce the curvature of the carbon fiber tow (less curvature) and be more flat than the carbon fiber tow in the B-rod body. There is not enough space to install metal gaskets in the type B tie rod group, and the CFRP rod body is directly in contact with the tie rod seat. When the tie rod group is under tension, the CFRP rod body is directly pressed on the pin of the tie rod seat.