Development of a Test Rig for Axial Strains Measurement in Automobile Wheel

In automobile wheel application, a test rig is vital and used to simulate conditions of the wheel in service in order to affirm the safety and reliability of the wheel. The present work designed a test rig for measuring axial strains in automobile wheel. The wheel used was a five-arm wheel (6JX14H2;ET 42) and Tyre (175 × 65 R 14). Experimental (EXP) test was carried out, with a radial load of 4750 N and inflation pressure of 0.3 MPa, to measure the axil strains which were converted to maximum principal strain values and, compared with data from Finite Element Analysis (FEA) using Creo-Element/Pro 5.0 at wheel’s contact angles of 90 degree (FEA 90 deg), 40 degree (FEA 40 deg) and 30.25 degree (FEA 30.25 deg), respectively. Results show that at the wheel’s point of contact with the ground, maximum principal strain values were highest at the inboard bead seat with a value of about 5.69 × 10-4 mm/mm, followed by the values at the well of about 5.66 × 10-4 mm/mm. The value at the outboard bead seat was least at about 2.22 × 10-4 mm/mm, which was due to the presence of spikes at this location that tends to resist imposed radial loads. However, the highest mean maximum principal strain values at the locations of inboard, well and outboard, were about 2.11 × 10-4 mm/mm, 3.78 × 10-4 mm/mm and .99 × 10-4 mm/mm, respectively. With the highest single value of about 5.69 × 10-4 mm/mm, the inboard bead seat was the most strained location of the wheel. Overall results showed that all values of maximum principal strains were below the threshold value of about 1 × 10-2 mm/mm. The values obtained for EXP and FEA could be said to be in close agreement when compared with the threshold value. With this in mind, the rig is recommended for use in related experimental procedures.

Radially loading rotary extrusion for manufacturing large-size conical cylinders with inner transverse high ribs

The Large-size Conical Cylinders with Inner Transverse High Ribs(LCCWITHR) can reduce the weight of the parts while maintaining high rigidity and strength. Radially Loading Rotary Extrusion(RLRE) forming technology can achieve integral forming of LCCWITHR through the synergy of radial and rotary movements of dies. The flow law of the material during the forming process is the key to forming large-size inner ribs. At present, there is no unified understanding of the metal flow law of RLRE forming technology. An analytical expression was derived to predict the Radial Direction(RD) deformation loads. The FE simulation and process experiment were carried out to investigate the effects of the inclination angle, thickness factor and transition arc radius of the split top dies on the spacing of the metal diversion plane, the metal flow velocity of the rib area and the final radius of the inner rib. The influence of the split top dies loading distance and the bottom die rotation angle of each pass on the inner radius of the inner rib was verified. And the optimal combination of dies shape parameters and loading paths which can make the metal flow orderly was obtained: the inclination angle is 140°, the thickness factor is 3.64, the transition arc radius is 16 mm;the top dies loading distance is 15 mm, the bottom die rotation angle is 45°.The FE simulation results have been found to be in close agreement with physics experiment.The research results reveal the metal flow law of rib growth in the RLRE of LCCWITHR, which lays a theoretical foundation for subsequent thorough research and process optimization.

Effects of the radial blade loading distribution and B parameter on the type of flow instability in a low-speed axial compressor

Previous studies showed that an axisymmetric hub-initiated disturbance defined as partial surge may initiate the stall of a transonic compressor; to reveal the instability evolution under full-span incompressible flow for different levels of hub loading and B parameter, an experimental investigation is conducted on a single-stage low-speed compressor. Experimental results show that under a uniform inflow condition without inlet flow distortion, a modal-type stall inception dominates in this low-speed compressor. When an inlet screen introducing hub distortion is used to increase the hub loading, a compressor stall is initiated by a modal wave, but large disturbances are present in the hub region before the compressor stall, which become stronger as the hub loading increases. Under high hub loading and large B parameter（implemented by adding hub distortion through an inlet screen and enlarging the outlet plenum volume, respectively）, a compressor stall is triggered by an axisymmetric hub-initiated disturbance, which is much different from the modal-like disturbances. The beginning of this axisymmetric disturbance may be captured over 800 rotor revolutions prior to the onset of stall, and the amplitude grows with time. The disturbance is hub-initiated because the disturbance signal at the hub is detected much earlier than that at the tip; meanwhile, the frequency of this axisymmetric disturbance changes with the length of the inlet duct. The characteristics of instability evolution in the low-speed compressor are also compared with those in a transonic compressor.

Large-Amplitude Oscillations of Hyperelastic Cylindrical Membrane Under Thermal-Mechanical Fields

In this paper,the nonlinear dynamic behaviors of a hyperelastic cylindrical membrane composed of the incompressible Ogden material are examined,where the membrane is subjected to uniformly distributed radial periodic loads at the internal surface and surrounded by a thermal field.A second-order nonlinear differential equation describing the radially symmetric motion of the membrane is obtained.Then,the dynamic characteristics of the system are qualitatively analyzed in terms of different material parameter spaces and ambient tem-peratures.Particularly,for a given constant load,the bifurcation phenomenon of equilibrium points is examined.It is shown that there exists a critical load,and the phase orbits may be the asymmetrie homoclinic orbits of the“oo”type.Moreover,for the system with two centers and one saddle point,the dynamic behaviors of the system show softening phenomena at both centers,but the temperature has opposite effects on the stiffness of the structure.For a given periodically perturbed load superposed on the constant term,some complex dynamic behaviors such as quasiperiodic and chaotic oscillations are analyzed.With the Poincare section and the maximum Lyapunov characteristic exponent,it is found that the ambient temperature could lead to the irregularity and unpredictability of the nonlinear system,and also changes the threshold of chaos.