Drag Force Simulation on Blast Loaded Fabric Roof
An important consideration in predicting the dynamic motion of highly deformable structures subject to blast loads is the effect of drag force. A representative example of this condition is a blast-loaded non-breathable fabric roof, typically used for tents or other aesthetic fabric structures. A fully coupled fluid-structure interaction (FSI) analysis to simulate the interaction of the fabric roof with the air domain is theoretically possible, but is complex and requires significant computational effort. This study presents an alternative approach of including drag force in LS-DYNA® without the need to employ any form of computational fluid dynamics (CFD). Using the keyword *LOAD_MOTION_NODE, the velocity component of each node of the roof fabric elements is used as a variable to calculate the nodal drag force using the dynamic pressure equation. The calculated drag force is then applied at each time step as a nodal force that is opposite to the direction of motion and parallel to the element normals that represent the roof fabric. Results from a validation study using this approach are presented, and a case study involving the response of an arched roof fabric canopy subjected to blast loads is also discussed.
https://www.dynalook.com/conferences/12th-european-ls-dyna-conference-2019/civil-engineering/hadjioannou_protection_engineering_consultants.pdf/view
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Drag Force Simulation on Blast Loaded Fabric Roof
An important consideration in predicting the dynamic motion of highly deformable structures subject to blast loads is the effect of drag force. A representative example of this condition is a blast-loaded non-breathable fabric roof, typically used for tents or other aesthetic fabric structures. A fully coupled fluid-structure interaction (FSI) analysis to simulate the interaction of the fabric roof with the air domain is theoretically possible, but is complex and requires significant computational effort. This study presents an alternative approach of including drag force in LS-DYNA® without the need to employ any form of computational fluid dynamics (CFD). Using the keyword *LOAD_MOTION_NODE, the velocity component of each node of the roof fabric elements is used as a variable to calculate the nodal drag force using the dynamic pressure equation. The calculated drag force is then applied at each time step as a nodal force that is opposite to the direction of motion and parallel to the element normals that represent the roof fabric. Results from a validation study using this approach are presented, and a case study involving the response of an arched roof fabric canopy subjected to blast loads is also discussed.
Hadjioannou_Protection_Engineering_Consultants.pdf