Fire modeling

Because of more stringent fire standards, manufacturers are responding by developing fire-resistant coatings, composites, and other materials that impart greater strength under severe conditions. It is critical to know how materials of various shapes and sizes will behave in specific applications. UL combines experimental data with sophisticated fire modeling not only to provide accurate classifications and certifications of building materials, but also to collect data not available from full-scale tests, such as stress in structural members or delivered water density to a burning commodity. This research provides supplemental data to help validate the complex computer models used to assess large-scale fire hazards.

Versatile applications

Information from modeling can be used to explore prototype designs before fire testing. Modeling can also be used to provide data not readily available from full-scale tests. For example, local stresses and strains on a fire door using ANSYS can provide clues to developing a more optimized fire door; fire dynamics simulator (FDS) can be used to determine the effect of sprinkler location below the ceiling or the influence of specific obstructions.

Modeling techniques

• Structural and thermal analysis using ANSYS finite element solvers, including coupled thermal and structural analysis
• Combustion and field modeling using the fire dynamics simulator (FDS) developed by researchers at the National Institute of Standards and Technology (NIST)
• Thermal resistance modeling using the finite element solver FIRES-T3

The UL advantage

Fire modeling is a continually evolving science that requires significant expertise to develop reliable input data and validate performance under a wide array of fire scenarios. Product engineers can leverage more than 100 years of UL experience to create and perform a variety of tests without assuming the overhead of expensive equipment, staff resources and opportunity costs. Close collaboration during product development reduces costs and accelerates time-to-market.

UL also develops input data that helps validate and improve the ability of fire models to evaluate a variety of characteristics. These include stress-strain relationships, modulus of elasticity (MOE), and modulus of rupture (MOR) for use in ANSYS; temperature-dependant thermal properties (thermal conductivity, specific heat) for use in ANSYS and FIRES-T3; and material ignition and burning characteristics, smoke yields, sprinkler drop size and flux measurements for use in the FDS model. These properties are validated using intermediate-scale testing.