The National Academies Press

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From page 63... ... The block method would use 4-ft square blocks of the foam, analogous to the current EMAS construction approach. The blocks would be constructed by adhering multiple smaller blocks together, followed by the potential addition of top and/or bottom cap materials. Read the entire page →
From page 64... ... Glass foam arrestor variants: block method (top) and monolithic method (bottom) Read the entire page →
From page 65... ... Metamodeling Build Combined Tire/Arrestor Models (LS-DYNA) Batch Simulations for Tire/Arrestor Combinations (LS-OPT) Read the entire page →
From page 66... ... 9.3. Testing Effort The testing effort for the glass foam material involved an extensive battery of mechanical and environmental tests. Read the entire page →
From page 67... ... . The glass foam material exhibited a characteristic crushable foam load history that rose to a plateau value, where it remained until the material approached full compression (Figure 9-6) Read the entire page →
From page 68... ... Average load history for glass foam material from low-rate platen tests, tall specimen. Strain [in./in.] Read the entire page →
From page 69... ... . The glass foam material compressed cleanly, leaving a smooth-sided hole in the block. Read the entire page →
From page 70... ... Figure 9-12 shows the overall pendulum apparatus with the glass foam blocks beneath it. Read the entire page →
From page 71... ... Figure 9-13. Post-test results from pendulum test for glass foam. Read the entire page →
From page 72... ... A high-fidelity model for the glass foam material was calibrated to match the test data (Figure 9-3, block 1) Read the entire page →
From page 73... ... Formulation The glass foam arrestor models were developed in LS-DYNA, a general-purpose finite element modeling code. Within LS-DYNA, a number of formulations exist for representing solids and fluids. Read the entire page →
From page 74... ... 2.9% • 3.65 x 8-in. cylinder • 10 psi hydrostatic pressure Hydrostatic Triaxial Test • Match stress at 5% compression 19% • Large block • Match stress–strain load curve with RMSE to 70% compression 8.4% Punch Test • Match energy absorption at 70% compression 1.2% Read the entire page →
From page 75... ... Since the test data showed a 6 to 10% variation for these two metrics, the model is within the experimental data scatter. Overall, the pendulum model validated that the glass foam material was well calibrated. Read the entire page →
From page 76... ... This approach enabled various depths to be rapidly configured within a single arrestor bed model. SPH particle sizes were chosen based on the tire size. Read the entire page →
From page 77... ... Aircraft Landing Gear Tire Designation Main Gear H29x9.0-15 CRJ-200 Nose Gear R18x4.4 Main Gear H44.5x16.5-21 B737-800 Nose Gear H27x7.7-15 Main Gear H49x19-22 B747-400 Nose Gear H49x19-22 Table 9-4. FEM tire library for glass foam arrestor models. Read the entire page →
From page 78... ... Two conditions defined the maximum penetration depth: 78 Tire presses down into arrestor Tire accelerates forward and is given an initial spin rate Tire continues forward and is allowed to f reely spin Steady-state vertical and drag loads are measured Tire begins above arrestor Figure 9-23. Sequencing method for glass foam arrestor model. Read the entire page →
From page 79... ... deep glass foam arrestor bed. Stronger drag loads (shown as the lower, more negative values) Read the entire page →
From page 80... ... Arrestor beds were designed for two different nose-gear loading criteria: 1. Limit Load Criterion, where the drag load applied to the nose strut cannot exceed the limit load for the nose gear (FAR Part 25.509) Read the entire page →
From page 81... ... Fleet design arrestor bed for glass foam arrestor system. Read the entire page →
From page 82... ... Landing Gear Forces - NOSE STRUT Nose Gear Drag Nose Gear Limit Load Nose Gear Ultimate Load Figure 9-26. Limit criterion glass foam arrestor design plots for B737-800 showing speed (top) Read the entire page →
From page 83... ... Landing Gear Forces - NOSE STRUT Figure 9-27. Ultimate criterion glass foam arrestor design plots for B737-800 showing speed (top) Read the entire page →
From page 84... ... . The glass foam arrestor concepts would require site preparation and paving similar to the current EMAS. Read the entire page →
From page 85... ... Cost Category Glass Foam System Current EMAS Site Preparation $ 0.68 $ 0.68 Installation $ 5.49 $ 3.83 Cost to Establish $ 6.17 $ 4.50 Percent of EMAS 137% Table 9-9. Estimated costs to establish glass foam arrestor, 150 x 300 ft, assuming Order 5200.9 costs for current EMAS, units of millions USD. Read the entire page →
From page 86... ... 9.7.5. Full-Scale Testing A full-scale aircraft overrun test of the glass foam arrestor bed may or may not be critical to approve and field such a system. Read the entire page →

From page 63...

... The block method would use 4-ft square blocks of the foam, analogous to the current EMAS construction approach. The blocks would be constructed by adhering multiple smaller blocks together, followed by the potential addition of top and/or bottom cap materials.