Foundation effects play a crucial role in sandwich fracture specimens with a soft core. Accurate estimation of deformation characteristics at the crack front is vital in understanding compliance, energy release rate and mode-mixity in fracture test specimens. Beam on elastic foundation analysis of moment- and force-loaded single cantilever beam sandwich fracture specimens is presented here. In addition, finite element analysis of the single cantilever beam specimen is conducted to determine displacements, rotations, energy release rate and mode-mixity. Based on finite element analysis, a foundation modulus is proposed that closely agrees with the numerical compliance and energy release rate results for all cases considered. An analytical expression for crack root rotation of the loaded upper face sheet provides consistent results for both loading configurations. For the force-loaded single cantilever beam specimen (in contrast to the moment-loaded case), it was found that the crack length normalized energy release rate and the mode-mixity phase angle increase strongly as the crack length decreases, a result of increased dominance of shear loading.
LiXCarlssonLA. The tilted sandwich debond (TSD) specimen for face/core interface fracture characterization. J Sandw Struct Mater1999; 1: 60–75.
6.
QuispitupaABerggreenCCarlssonLA. Design analysis of the mixed mode bending sandwich specimen. J Sandw Struct Mater2010; 12: 253–272.
7.
LuTJXiaZCHutchinsonJW. Delamination of beams under transverse shear and bending. Mater Sci Eng A1994; 188: 103–112.
8.
LiSWangJThoulessMD. The effects of shear on delamination in layered materials. J Mech Phys Solids2004; 52: 193–214.
9.
TimoshenkoSGoodierJN. Theory of elasticity, New York: McGraw-Hill, 1970.
10.
BarberJR. Intermediate mechanics of materials, Dordrecht, the Netherlands: Springer, 2011.
11.
AndrewsMGMassabòR. The effects of shear and near tip deformations on energy release rate and mode mixity of edge-cracked orthotropic layers. Eng Fract Mech2007; 74: 2700–2720.
12.
SørensenBFJørgensenKJacobsenTKet al.DCB-specimen loaded with uneven bending moments. Int J Fract2006; 141: 163–176.
13.
Lundsgaard-LarsenCSørensenBFBerggreenCet al.A modified DCB sandwich specimen for measuring mixed-mode cohesive laws. Eng Fract Mech2008; 75: 2514–2530.
14.
CantwellWJDaviesP. A test technique for assessing core-skin adhesion in composite sandwich structures. J Mater Sci Lett1994; 13: 203–205.
15.
RatcliffeJGReederJR. Sizing a single cantilever beam specimen for characterizing facesheet-core debonding in sandwich structure. J Compos Mater2011; 45: 2669–2684.
16.
RinkerMRatcliffeJGAdamsDOet al.Characterizing face sheet/core disbonding in honeycomb core sandwich structure2013. NASA Technical Publication TP-2013-21. Available at: https://ntrs.nasa.gov/search.jsp?R=20130010408.
17.
Ratcliffe J and Krueger R. Face sheet/core disbonding in sandwich composite components: a road map to standardization: test method development. In: 11th international conference on sandwich structures, Dania Beach, FL, 20–22 May, 2016.
18.
KanninenMF. An augmented double cantilever beam model for studying crack propagation and arrest. Int J Fract. 9: 83–92.
19.
FrostigYBaruchMVilnayOet al.High-order theory for sandwich-beam behavior with transversely flexible core. J Eng Mech1992; 118: 1026–1043.
20.
PhanCNFrostigYKardomateasGA. Analysis of sandwich beams with a compliant core and with in-plane rigidity – extended high-order sandwich panel theory versus elasticity. J Appl Mech2012; 79: 41001.
21.
LiXCarlssonLA. Elastic foundation analysis of tilted sandwich debond (TSD) specimen. J Sandw Struct Mater2000; 2: 3–32.
22.
Weissman-BermanDPetrieGLWangM. Flexural response of foam-cored FRP sandwich panels. Soc Nav Archit Mar Eng1988, pp. 96.
23.
MassabòRCavicchiA. Interaction effects of multiple damage mechanisms in composite sandwich beams subject to time dependent loading. Int J Solids Struct2012; 49: 720–738.
24.
QuispitupaABerggreenCCarlssonLA. On the analysis of a mixed mode bending sandwich specimen for debond fracture characterization. Eng Fract Mech2009; 76: 594–613.
BerggreenCSimonsenBCBorumKK. Experimental and numerical study of interface crack propagation in foam-cored sandwich beams. J Compos Mater2006; 41: 493–520.
SunCTPandeyRK. Improved method for calculating strain energy release rate based on beam theory. AIAA J1994; 32: 184–189.
29.
PandeyRKSunCT. Calculating strain energy release rate in cracked orthotropic beams. J Thermoplast Compos Mater1996; 9: 381–395.
30.
WangJQiaoP. Interface crack between two shear deformable elastic layers. J Mech Phys Solids2004; 52: 891–905.
31.
SuoZHutchinsonJW. Interface crack between two elastic layers. Int J Fract1990; 43: 1–18.
32.
NilssonK-FAspLEAlpmanJEet al.Delamination buckling and growth for delaminations at different depths in a slender composite panel. Int J Solids Struct2001; 38: 3039–3071.
33.
BrunoDGrecoF. Mixed mode delamination in plates: a refined approach. Int J Solids Struct2001; 38: 9149–9177.
