Component Tests of Cone Fenders and Cylindrical Fenders
For the axial compression simulation of the rubber cone type fenders, two rigid plates were used to sandwich the cone. The rubber cone had constant stress solid hexahedral elements. Since the cone had an irregular shape and thick walls, solid hexahedral elements were used in lieu of shell elements. The dimensions of the cone were 12 in. high, an 11.6 in. top diameter, a 2 in. wall thickness, and a 10.7 degree slope. Other cone geometries were explored, but the 12-in. high cone provided the most uniform deformation and adequate energy-absorbing capacity.
The sequential deformation of the cone is shown in Figure 82 along with an enlarged cross-section view at 16 ms.
Preliminary simulation indicated that the 12-in. (304-mm) high conical rubber shape would absorb 92 k-in. (10.4 kJ) of energy with 8½ in. (216 mm) of deflection.
A physical component test was required to validate the simulation. Due to the limited availability for pre-made conical fender sizes, cylindrical shapes were further explored since the components could be mandrel-wrapped in any size without a custom mold.
The energy-absorbing capacity of axially-loaded cylinders was evaluated using the generic rubber model previously used in the conical model. Constant stress hexahedral solids elements were used, and the model is shown below.
The diameter and thickness was varied on 10-in. (254-mm) long cylinders. Two 12-in. (305-mm) inner diameter (ID) cylinders had a wall thickness (t) of 1 in. (25 mm) and 2 in. (51 mm). Two 8-in. (203-mm) inner diameter cylinders had a wall thickness of 1 in. (25 mm) and 2 in. (51 mm).
3. Component Tests
From the preliminary finite element simulations, three different cylinders were selected for further investigation. The dimensions and durometer of the three different rubber cylinders are shown in the following Table. One cylinder was 60-durometer EPDM. The other two cylinders were 80-durometer EPDM. Component testing was needed to determine the dynamic properties and behavior of the cylinders as well as to improve the finite element simulations.
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