SHORT DESCRIPTION

State-of-the-art finite-element modeling of structural response to blast and impact loads.

OVERVIEW

NLFlex is one of the most advanced software packages available for modeling the response of structures to blast and impact loads. It is based on a time-domain finite-element approach to modeling complex nonlinear behavior of structures.

NLFlex has proven to be a powerful tool for Department of Defense and counterterror applications. It has been applied to a wide range of problems involving extreme loads on structures, including:

• Analysis of hardened structures subjected to conventional and nuclear weapon effects
• Simulation of national infrastructure exposed to terrorist threats
• Progressive collapse simulations
• Simulations of aircraft impact into buildings and other structures
• Response of deeply buried structures to high stress-loading

NLFlex uses an explicit time-integration algorithm that allows the code to simulate large models efficiently. The program’s accuracy has been verified through analysis of standard benchmark problems for which analytic solutions are known. Code results have also been compared with those from other computer programs and with experimental data. NLFlex has been used in a number of explosive field tests over the past twenty years, validating its advanced constitutive models and computational algorithms against real-world events.

CAPABILITIES

NLFlex’s wide range of capabilities includes:

• 2-D and 3-D models
• Time-domain or static simulations using a dynamic relaxation approach
• Efficient radiation (or absorbing) boundary conditions for treating "infinite" media
• Element libraries including continuum and structural finite elements: shells, beams, and bars.

NLFlex can perform parallel computations on computer systems that support it. Advanced constitutive models for representing concrete, geologic materials, steel and other metals, and composites are available.

NLFlex computational models typically range in size from 10,000-element 2-D models that require less than one minute run-time on a workstation to multimillion-element 3-D models that require hours or days of simulation time. Model size is limited only by the available computer memory.

Output includes time histories and/or snapshots of field variables such as displacement, velocity, pressure, stress, and strain. Data are saved during an analysis for post-processing. The data structures of output files are kept simple so that data can be easily manipulated for use with the user’s on-site graphics capabilities.

The NLFlex package includes REVIEW, a post-processor that can plot results and display on-screen movies. Experimental results are easily imported for cross-plotting. Time-shifting, scaling, differentiation, integration, and other functions are included to facilitate comparisons.

More information can be obtained about this product by emailing flex_support@wai.com.