Analysis of Structural Characteristics of Rubber Bushings

By Mehboob Ali Meghani

Modern automotive suspensions use a large number of flexible connections such as rubber bushings to meet the needs of vehicle damping and noise reduction. The precise design of the suspension also requires matching of various performance parameters of the rubber bushing. Rubber bushings are widely used. There are many researches on the influence of rubber bushings on the performance of automobiles and their optimization and isolation. However, there are relatively few studies on the structure, parameters and effects on the performance of the car bushings.

The role of rubber bushings:

The introduction of rubber components in the suspension system can greatly improve the isolation effect of the system in the high frequency range without changing the isolation characteristics of the low frequency band, and help the suspension system to isolate the high frequency natural vibration and reduce the unevenness caused by the road surface. In-car noise. Therefore, by designing the characteristics of the rubber bushing, vibration and impact transmitted from the road surface can be alleviated, and steering stability can be ensured. Rubber bushings have the following advantages over other parts:

  1. Since the elastic mold of rubber is smaller than that of metal, the effect of vibration isolation and noise reduction is remarkable.
  2. The shape of the rubber is not limited, and the rigidity in each direction can be freely selected within a certain range, and the spring stiffness ratio of the three directions can be appropriately selected.

AA-TOP enterprise is specialized in producing Engine Mount, Strut Mount, Control Arm, Tie Rod, Bushing, Timing Belt, V-Ribbed Belt and Cogged V-Belt. Products had passed ISO/TS16949 quality management system,and exported to more than 100 countries, inclucing Europe, Middle East, Southeast Asia,etc. Long term cooperation with big buyers and famous brands had been established in Germany, USA, Turkey and other countries.

          3- It is easy to firmly bond with the metal parts, so that the rubber bushing can bear the load in multiple directions, which simplifies the structure and reduces the quality of the whole vehicle.

         4- The internal friction of the vulcanized rubber is larger than the internal friction of the metal, and tends to increase as the frequency increases, so the amplitude is small at the time of resonance.

Rubber bushing applications:

A rubber bushing commonly used in suspensions consists of an intermediate rubber body and a metal sleeve. In order to improve durability, it is necessary to appropriately pre-compress the intermediate rubber body in the radial direction, and the pre-compression stroke corresponds to 10% to 30% of the thickness of the rubber. When the rubber bushing is used, the outer cylinder is fixed, and the inner cylinder is deformed correspondingly with the movement of the wheel or other parts, and the maximum deformation can reach 100%, and the deformation influence characteristic directly affects the kinematics and dynamic performance of the suspension.

The main applications of rubber bushings in a certain model are: Sub-frame rubber bushing: The front sub-frame and the rear sub-frame are respectively flexibly connected to the underbody by four bushings. The upper control arm of the front suspension is connected to the vehicle body through two rubber bushings, one end of the front lower control arm and the lower rear control arm is connected to the sub-frame through a rubber bushing, and the other end is connected to the steering knuckle through the ball head.

Rubber bushing fatigue performance:

Fatigue damage is a problem that often occurs in rubber bushings in actual use. The fatigue life should be improved from the following aspects.

  1. In the product design, the stress concentration of the rubber bushing should be avoided, and the rubber part should not have excessive stress and deformation; in addition, the amount of rubber in the product should not be too small, because the rubber bushing will be inside the rubber when subjected to a large load. If the amount of rubber is too high, it has a large heat capacity, which can delay the occurrence of damage.
  2. In order to resist the influence of the atmospheric environment on rubber products, the filler particles used in the rubber material have a small diameter, and the amount and type of the compounding agent have a great influence on the service life.
  3. During production, the surface precision of the metal mold processing should be improved to avoid defects on the rubber surface and its vicinity. While the protection is carried out, the rubber mixture should be made uniform, no bubbles are generated, and the vulcanization time and the vulcanization temperature are mastered.
  4. When opening the position of the rubber injection hole, the flow of the rubber in the cavity should be minimized, that is, the loss of the adhesive at the key parts should be minimized, and the cavity should be filled as much as possible.

According to the analysis, the rubber bushing needs to comprehensively consider the installation space, the force state, the performance and the life factor in the structural design, so as to determine the type of bushing, the rubber shape and the reasonable process flow. AA-TOP can provide professional advice.

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Mehboob Ali Meghani

Mehboob Ali is an Entrepreneur and a Social Activist. He is also a contributor at Business Innovators Magazine, Small Business Trendsetters and Marketing Insiders.