Wonder of Science

Topics: Reinforced concrete, Finite element method, Metre Pages: 7 (1622 words) Published: May 8, 2012

This paper describes numerical simulation of a selected soft missile impact small scale test. The main aim of the testing program is to provide data for the calibration and verification of the numerical simulation models for soft missile impact time-history simulation. The experiments are conducted both with dry and fluid filled missiles. The objective of the tests with fluid filled missiles is to investigate the release speed and the droplet size of the fluid spray release in the impact. The spray release velocity and droplet size are needed as an input data for numerical simulation methods to assess the spread of the liquid in the impact. The second object of the testing program is to develop the numerical methods for predicting the response of reinforced concrete structures to impacts of soft missiles. The pre-test and post-test analyses are used for simulating the impact load time-history and structural behavior of both the missile and the target with the aid non-linear finite element method. INTRODUCTION

The events of September 11th have emphasized the need to design protective structures for important constructions against external impact loads, caused e.g. by colliding vehicles, and to analyze carefully the possible consequences of such events, taking into account the existing experience and information. In the open literature there are some fairly well documented test results on the subject of deformable missiles to be used as references in developing and calibrating the finite element simulation models and assessing the obtained numerical results. However, test results for fluid filled soft projectiles are not available in the open literature. In order to get any confidence with the simulation results, experimental, recorded data is needed for verification. The main objective of the small scale test program is to develop and calibrate finite element simulation models for reinforced concrete structures impacted by deformable missiles filled with fluid. SPECIFICATION OF THE TESTS TO BE SIMULATED

The missile of the test #643 is the dry aluminum pipe with 1.5 meter length and 50 kilograms mass and 250 millimeter cross-section diameter. The impact velocity is 128 m/s. The impact target is the square simply supported reinforced concrete slab of 150 millimeters thickness and with side length of 2 meters. There is only longitudinal reinforcement in the slab with reinforcement ratio of 0.70 % in each surface and in each direction.



Transactions, SMiRT 19, Toronto, August 2007 Transactions, SMiRT 19, Toronto, August 2007 .

Paper # ???? Paper # J08/1

Fig. 1. Schematic presentation of the aluminum projectile used in simulated test #629. To simulate the test numerically the finite element model of the missile was constructed. The number of degrees of freedom in the model was about 15000. The ABAQUS/EXPLICIT and MSC/DYTRAN programs were used for the simulation. The reaction force time history in the impact direction from one point of the impacting front edge of the missile is determined. Also the displacement and velocity time histories in the impact direction of one point in the rear edge of the missile are determined. The deformed shape of the missile at end of the impact is also determined in the numerical simulation task. The test set-up has been used during the year 2005 to obtain preliminary information on the missile impact. The purpose of the preliminary tests was to gain experience and proficiency in the monitoring of the and in numerical simulation methods in order to calculate the reaction force timehistory during impact. In the preliminary tests a wide spectrum of different impact velocities and masses were used. The weights of the missiles varied between 22 and 95 kilograms and the impact speeds of the missiles varied between 70 and 170 meters per second. The first sixteen missiles in 2005 were spiral-welded steel pipes and the last four were aluminum pipes. Seven of the missiles...
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