The modeling clay is an oil-based soft, flowable, and pliable material made from waxes and oils. Besides its primary use for making sculptures, the modeling clay is commonly used to evaluate bulletproof vests and simulate metal manufacturing processes by conformation. In ballistic tests, the clay is used to retain the deformation of the rear face of body armors; and in the study of metal forming processes, it is used as a physical model to provide information on the plastic flow. However, its mechanical dynamic behavior is not entirely understood. In this study, Plastilina Roma No. 1 modeling clay was mechanically characterized using the power-law constitutive model at medium strain rates . The material parameters were determined using a penetration model based on the Cavity Expansion Theory and an inverse technique involving the comparison of the model with experimentation. The optimum set of constitutive parameters was found by reducing the difference of the calculated penetration profile and the measurements from a drop test. This optimization process was programmed on the MATLAB–Simulink environment. The determined material parameters were validated by comparing the results from a computational model with three test set-ups. Finite element model results show good concordance with experimental measurements.
CouncilNR. Phase I report on review of the testing of body armor materials for use by the U.S. Army: letter report. Washington, DC: The National Academies Press, 2009.
2.
CouncilNR. Testing of body armor materials for use by the U.S. Army —phase II: letter report. Washington, DC: The National Academies Press, 2010.
3.
CouncilNR. Testing of body armor materials: phase III. Washington, DC: The National Academies Press, 2012.
4.
SofuogluH. A technical note on the role of process parameters in predicting flow behavior of plasticine using design of experiment. J Mater Process Tech2006; 178: 148–153.
5.
PertenceACetlinP. Analysis of a new model material for the physical simulation of metal forming. J Mater Process Tech1998; 84: 261–267.
CalvitHHRaderDMelvilleJ. Some wave-propagation experiments in plasteline-clay rods. Exp Mech1968; 8: 418–423.
8.
GoodeveCF. A general theory of thixotropy and viscosity. T Faraday Soc1939; 35: 342–358.
9.
McClayKR. The rheology of plasticine. Tectonophysics1976; 33: T7–T15.
10.
CrandallSHKurzweilLGNigamAK, et al. Dynamic properties of modelling clay. Technical report, NASA, Washington, DC, 1970.
11.
CrandallSHKurzweilLGNigamAK. On the measurement of Poisson’s ratio for modeling clay. Exp Mech1971; 11: 402–413.
12.
ChijiiwaKHatamuraYHasegawaN. Characteristics of plasticine used in the simulation of slab in rolling and continuous casting. J Iron Steel Inst Japan1980; 66: 496–505.
13.
FinérSKivivuoriSKleemolaH. Stress-strain relationships of wax-based model materials. J Mech Work Technol1985; 12: 269–277.
14.
SofuogluHRastyJ. Flow behavior of plasticine used in physical modeling of metal forming processes. Tribol Int2000; 33: 523–529.
15.
AdamsMJAydinIBriscoeBJ, et al. A finite element analysis of the squeeze flow of an elasto-viscoplastic paste material. J Non-Newton Fluid1997; 71: 41–57.
16.
PathakKSoniASharmaM, et al. An inverse technique for evaluation of flow parameters of modeling materials using extrusion. Exp Techniques2013; 37: 16–22.
17.
HuangZLucasMAdamsM. A numerical and experimental study of the indentation mechanics of plasticine. J Strain Anal Eng2002; 37: 141–150.
18.
LiYGaoXLFournierA, et al. Two new penetration models for ballistic clay incorporating strain-hardening, strain-rate and temperature effects. Int J Mech Sci2019; 151: 582–594.
19.
GadAGaoXL. Modeling of deformations of Roma Plastilina# 1 clay in column-drop tests by incorporating the coupled strain rate and temperature effects. Mech Adv Mater Struc2020; 27: 1154–1166.
20.
GilsonLRabetLImadA, et al. Experimental and numerical characterisation of rheological properties of a drop test response of a ballistic plastilina. Forensic Sci Int2020; 310: 110238.
21.
GilsonLRabetLImadA, et al. Ballistic impacts experiments and plastilina/protection systems’ modeling. In: FangueiroRRanaS (eds) Advanced materials for defense. New York: Springer, 2020, pp. 129–136.
22.
Office of Law Enforcement Standards and National Institute of Standards and Technology. Ballistic resistance of body armor. NIJ Standard-0101.06, July2008. Washington, DC: U.S. Department of Justice.
23.
BishopRFHillRMottNF. The theory of indentation and hardness tests. Proc Phys Soc1945; 57: 147.
24.
HillR. The mathematical theory of plasticity, vol. 11. Oxford: Oxford University Press, 1950.
25.
HopkinsHG. Dynamic expansion of spherical cavities in metals. Prog Solid Mech1960; 1: 85–125.
26.
ForrestalMJOkajimaKLukVK. Penetration of 6061-t651 aluminum targets with rigid long rods. J Appl Mech1988; 55: 755.
ForrestalMTzouDAskariE, et al. Penetration into ductile metal targets with rigid spherical-nose rods. Int J Impact Eng1995; 16: 699–710.
29.
WarrenTForrestalM. Effects of strain hardening and strain-rate sensitivity on the penetration of aluminum targets with spherical-nosed rods. Int J Solids Struct1998; 35: 3737–3753.
30.
DurbanDMasriR. Dynamic spherical cavity expansion in a pressure sensitive elastoplastic medium. Int J Solids Struct2004; 41: 5697–5716.
31.
MasriRDurbanD. Dynamic spherical cavity expansion in an elastoplastic compressible mises solid. J Appl Mech2005; 72: 887–898.
32.
CohenTMasriRDurbanD. Analysis of circular hole expansion with generalized yield criteria. Int J Solids Struct2009; 46: 3643–3650.
33.
JonesSERuleWKJeromeDM, et al. On the optimal nose geometry for a rigid penetrator. Comput Mech1998; 22: 413–417.
34.
JonesSERuleWK. On the optimal nose geometry for a rigid penetrator, including the effects of pressure-dependent friction. Int J Impact Eng2000; 24: 403–415.
35.
DurbanDBaruchM. On the problem of a spherical cavity in an infinite elasto-plastic medium. J Appl Mech1976; 43: 633–638.
36.
DurbanDFleckNA. Spherical cavity expansion in a Drucker–Prager solid. J Appl Mech1997; 64: 743–750.
37.
BuchelyMMaranonA. Spherical cavity expansion approach for the study of rigid-penetrator’s impact problems. Appl Mech2020; 1: 20–46.
38.
BuchelyMMaranonA. Study of steady cavitation assumptions in strain-rate-sensitive solids for rigid projectile penetrations. Acta Mech2016; 227: 2969–2983.
39.
BuchelyMFMaranonA. An engineering model for the penetration of a rigid-rod into a Cowper–Symonds low-strength material. Acta Mech2015; 226: 2999–3010.
40.
ASTM D618:2008. Standard practice for conditioning plastics for testing.
41.
ASTM D695:2002. Standard test method for compressive properties of rigid plastics.
42.
SegletesSB. Modeling the penetration behavior of rigid spheres into ballistic gelatin. Technical report no. ARL-TR-4393, March2008. Aberdeen Proving Ground, MD: U.S. Army Research Laboratory.
43.
ChaSH. Comprehensive survey on distance/similarity measures between probability density functions. Int J Math Model Method Appl Sci2007; 1: 300–307.
