Pukyong National University
The Computer Aided & Structural Analysis Lab at Pukyong National University has been conducting several research studies regarding automotive AC hoses. An automotive AC hose is one of the most important parts in an automotive vehicle. The hose is composed of rubber materials with reinforced braids and is used to supply a high-pressure refrigerant fluid between the engine and the air conditioner. Since the engine produces a vibration when it’s operated, the vibration of the engine is conveyed to the hose as dynamic loading. This may potentially cause a failure in an AC hose, resulting in a refrigerant leakage.
A three dimensional model of the automotive AC hose, shown in Fig. 1, is modeled using MSC.Marc. Marc is a powerful tool to solve nonlinear problems such as contact and hyperelastic material analysis. In this case, the contact bodies are divided into three deformable contact bodies: nipple, sleeve, and hose. The rubber materials are generalized by the mooney-rivlin model. Two kinds of dynamic analysis are conducted in this work. First, the dynamic modal analysis is used to assess the dynamic characteristics of the AC hose structure. Secondly, the dynamic transient analysis is used to investigate the dynamic response of the hose component due to the dynamic loading and the dynamic behavior of the reinforced braid.
Fig.1 Finite Element Method and the real configurations of automotive AC hose
Fig. 2 shows the mode shapes for first and second natural frequencies calculated using the lumped-mass system. The first mode shows the swing mode and the second mode shows the bending mode.
Fig. 2 First and second mode shapes of the automotive AC hose
Fig. 3 shows Cauchy stress contour of the hose. The stress concentrations are located in the braid layers because the mobility of the braid layers is restrained as the result of swaging process.
Fig. 3 Cauchy stress contour of the hose
Fig.4 shows the contour of displacement in y-direction. The peak value of displacement response is 3.229 mm with downward direction at 0.0448 s. This result is very important to determine the optimum layout of the hose under the operating condition.
Fig. 4 Contour of displacement response in y-direction and Time history of the displacement response in y-direction at maximum displacement region
By Christian Wijaya