Characterization of Fraglight Non-Woven Felt and Simulation of FSP's Impact in it Authors: Sidney Chocron; A. Pintor; D. Cendon; C. Rosello; V. Sanchez- Galvez; UNIVERSIDAD POLITECNICA DE MADRID (SPAIN) ESCUELA TECNICA SUPERIOR DE INGENIEROS DE CAMINOS   Abstract: The non-woven felt known commercially as Dyneema Fraglight has an outstanding performances stopping fragments. The objective of this project is to understand the reason for this performance by means of four different approaches: 1) Through mechanical characterization varying size, direction, temperature and strain rate of specimens; 2) Ballistic characterization to obtain residual velocity curves and high speed photography; 3) Numerical simulations of static and ballistic tests; 4) Analytical modeling. All the approaches were covered, although the analytical work would need more work to complete. The mechanical characterization has shown that the felt is orthotropic, very size dependent, that it weakens appreciably at 100 C and up to strain rates of 10(exp 3)S(exp -1) its properties do not suffer a large modification. The ballistic tests show that the felt is actually better than what the manufacturer claims (with the boundary conditions used in this project) . The numerical simulations confirm that the huge deformation suffered by the felt during the ballistic impact is the key for its outstanding performance. An analytical simulation of a non-homogenous, non-linear and under very high strains is extremely difficult from first principles, though a constitutive equation for an elastic, orthotropic fibrous material, with arbitrary distribution of fibers has been developed.