Aging Behaviors of Silicone Rubber Composite Materials under Outdoor Environment

We investigated the aging effect on the chemical structure of silicone rubber composite materials under outdoor environment. The variations of low molecular weight siloxanes in silicone rubber were probed by gas chromatography-mass spectrometry during the degradation process. The experimental results indicate that a series of cyclic siloxanes exist in both the virgin and aged silicone rubber samples, while the additional low molecular weight siloxanes（hexamethyl cyclotrisiloxane） only appear in the aged samples. Meanwhile, the total amounts of low molecular weight siloxanes in the aged samples are much less than those in the virgin ones. The loss of low molecular weight siloxanes is induced by the chain scission and depolymerization.

Simulation and Experimental Study on Load-bearing Deformation Characteristics of 11R22.5 Vehicle Retreaded Tire

The finite element bearing deformation simulation was implemented on 11.00R22.5 retreaded tires by ANSYS software in the paper in order to further clarify the bearing deformation characteristics of retreaded tires and improve the performance of retreaded tires effectively.The characteristic laws of bearing radial deformation and bearing lateral deformation of retreaded tire and new tires of the same model under different working conditions were obtained through load deformation tests.The radial deformation calculation results,simulation results and measured results of retreaded tires were comparatively analyzed.The calculation formula of bearing radial deformation of retreaded tires was proposed based on the linear regression principle.The difference of bearing deformation characteristics and ground area characteristics of retreaded tires and new tires were comparatively analyzed.The results showed that the radial and lateral deformation of retreaded tires and new tires is increased with the increase of radial load when the tire pressure was constant,and the increase trend is approximately linear.The radial stiffness of retreaded tires is similar to that of new tires under certain tire pressure and low load.The radial stiffness of retreaded tires is larger than that of new tires,and the stiffness difference is increased with the increasing of load under constant tire pressure and high load.Rubber aging phenomenon in retreaded tire carcass have an impact on the bearing deformation characteristics of retreaded tires,thereby producing great impact on the remaining service life of retreaded tires.