40.3 Experimental Setup 40.3.1 Outer Tube A pressure vessel facility with a maximum allowable hydrostatic pressure of 10.3 MPa (1,500 psi) was fabricated for performing tube-in-tube experiments. A schematic diagram of the pressure vessel can be seen in Fig. 40.2. The pressure vessel (outer tube) has an inner diameter of 0.178 m (7.000), outer diameter of 0.215 m (8.500) and a length of 1.82 m (7200). The material chosen for the outer tube was SA 106 grade-B carbon steel, which satisfies ASME pressure vessel code. The vessel was mounted horizontally on an I-beam section as shown in Fig. 40.2. The outer tube contains eight dynamic pressure transducers to capture the pressure histories during the implosion event. These pressure transducers were flush-mounted to the inner wall of the pressure vessel to capture the pressure histories without disturbing wave propagation inside water. Six pressure transducers were placed on the wall of the vessel with 0.304m(1200) interspacing and two transducers were placed on the end caps. Two static pressure transducers (electronic and dial gage) were also placed on the end caps of the vessel to monitor the hydrostatic pressure inside the vessel during experiments. 40.3.2 Vessel Pressurization After placing the implodable volumes at the desired location (axially centered and concentric), the vessel was closed and pressurized by an electric hydrostatic test pump. The pressurization rate was kept relatively slow (~1 MPa/min) in order to minimize the dynamic pressurization effects. As the implosion of the specimen occurs, a small noise is generated along with a rapid pressure drop in the hydrostatic pressure inside vessel. At this point, the data acquisition system was triggered, which stored the data 10 s before the trigger point. Fig. 40.2 Implosion tube-in-tube experimental setup 40 Implosion of a Tube Within a Closed Tube: Experiments and Computational Simulations 329
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