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By 袁春凤 (Tiffany)
Basic knowledge of shock absorbing rubber products
1. Static stiffness: refers to the ratio of the change of pressure (or tensile force) to the change of displacement in a given displacement range. The static stiffness must be measured within a certain displacement range. The static stiffness values measured in different displacement ranges are different, but some families require the change curve measured in the whole displacement range.
2. Dynamic stiffness: It refers to the ratio of the change of pressure (or tensile force) to the change of displacement of damping rubber in a certain displacement range and a certain frequency.
3. dynamic magnification: the ratio of the dynamic stiffness to the static stiffness measured by the damping rubber in a certain range of displacement.
4. Loss coefficient: There is a phase difference between the deformation of rubber and the stress of rubber in the course of the force acting on damping rubber, and the stress of rubber is generally ahead of the phase angle of the deformation of rubber.
5. Torsional stiffness: refers to the ratio of torsional moment to torsional angle of damping rubber within a certain range of torsional angle.
6. Durability: It refers to the number of times of vibration when the rubber is in good condition after n times of reciprocating vibration under certain preloading load, amplitude and vibration frequency in a certain direction.Thanks for the help and support of Chongqing Feilong Jiangli Auto Parts technical department.
By 袁春凤 (Tiffany)
Fatigue life prediction of rubber bushing in vehicle system
1.Response analysis of rubber bushing under random excitation The Monte Carlo method is used to simulate the random excitation spectrum.
2. The fatigue life calculation of rubber bushing under random load can calculate the maximum strain energy density of rubber bushing under different excitation by using the response characteristics of rubber bushing under engine and road excitation obtained previously. The fatigue life of rubber bushing can be calculated under different load conditions. The maximum strain energy density U = 0.5134Nmm2 and the fatigue life N = 771371 were predicted under the excitation of engine speed n = 3000r/min and class B pavement, while U = 0.6893Nmm2, N, = 146774 under the excitation of engine speed n = 3000/min and class D pavement.(Thanks for the help and support of Chongqing Feilong Jiangli Auto Parts technical department.)
3. The test verification of the front sub-frame module is expensive because of the fatigue test of the whole vehicle system. Now the former sub-frame module is the research object, and the calculation results are compared with the test results. The front sub-frame is installed in accordance with its layout in the vehicle, and the six points connected with the body on the sub-frame are restrained. Sinusoidal excitation is carried out at the midpoint of the rear beam, and the maximum frequency which can be reached under the condition of satisfying the amplitude of the force is taken as the test frequency. The amplitude of force is 2.45.2kN. Fatigue failure criteria of rubber bushing: 2mm crack (equivalent to 20% of tensile coefficient).
By 袁春凤 (Tiffany)
Introduction of defects in rubber products vulcanizing
1.Lack of glue: due to insufficient weight or poor fluidity, some defects should be found in rubber parts.
2.Degumming: the failure of rubber and frame inserts will result in disengagement or separation.
3.Bubbles: also known as "bulging", because the gas is coated in the rubber epidermis and the formation of local epidermis blistering phenomenon; Thanks for the help and support of Chongqing Feilong jiangli’s Technical department.
4.Rotten bubbles: also known as "pit gas", because the gas has not been discharged from the cavity, so that the die corner of the rubber cavity is less sulfur sticky, and protruding from the surrounding rubber surface phenomenon
5.Gel cracking: a phenomenon of cracking on the glue surface.
6.Under sulfur: the inner surface of the gum is microporous, and the exterior is uplifted and deformed.
7.Sticking mould: the phenomenon that the local glue of vulcanized product is adhered to the wall of the mold cavity.
8.Hot die: also known as curling edge, "bite edge" and so on, refers to the product parting line is not smooth, cracks, serrated waste edge and other phenomena.