14
3.4 Conclusion
This preliminary study observed the difference in failure modes in a layered adhesive-substrate system under the same geometric conditions. Samples exhibited clear delamination behavior under quasi-static load conditions. Under these conditions,
Sylgard
®
184 showed large displacements and significant delamination with very low applied loads. In contrast, epoxy materials, SC-15 and TGDDM, produced higher shaft loads for a low displacement. These materials also exhibited delamination
behavior before a final fracture of the adhesive. To observe the dynamic load condition, samples were loaded with a shaft
velocity of 5 m/s, producing higher input loads than those measured under quasi-static conditions. For this condition,
Sylgard
®
184 showed significant resistance to delamination, and no fracture was observed. Both epoxy materials showed no
apparent delamination behavior, instead of failing due to fracture at the boundary of the substrate. These results show some
significant differences in the behavior of adhesives at different loading rates. With further improvements to sample design
and measurement systems, this is a promising technique to study these behaviors in more detail.
Acknowledgments The authors would like to thank their colleagues from the Impact Science Laboratory at Purdue University for their assistance
and support in understanding and improving this work.
References
1. Rolfe, E., Kelly, M., Arora, H., Hooper, P.A., Dear, J.P.: X-ray CT analysis after blast of composite sandwich panels. Proc. Eng. 167,
176–181 (2016)
2. Dear, J.P., Rolfe, E., Kelly, M., Arora, H., Hooper, P.A.: Blast performance of composite sandwich structures. Proc. Eng. 173, 471–478 (2017)
3. Daniel, I.M., Abot, J.L., Schubel, P.M., Luo, J.J.: Response and damage tolerance of composite sandwich structures under low velocity impact.
Exp. Mech. 52, 37–47 (2012)
4. Wan, K., Liao, K.: Measuring mechanical properties of thin flexible films by a shaft-loaded blister test. Thin Solid Films. 352, 167–172 (1999)
5. O’Brien, E.P., Case, S.L., Ward, T.C.: Critical and subcritical adhesion measurements of a model epoxy coating exposed to moisture using the
shaft-loaded blister test. J. Adhes. 81, 41–58 (2005)
Fig. 3.3 (a) Load-displacement data for quasi-static blister experiments. (b) Image from final failure of sample SC15-1 under quasi-static loading.
Point (1) denotes the boundary of the growing delamination and (2) marks the location of fracture of the adhesive. (c) Image of SC15 adhesive
failure under dynamic loading. (1) Marks the location of the ring fracture at the substrate boundary and (2) marks the location of a tensile fracture
at the location of the shaft
S. Paulson et al.
3.4 Conclusion
This preliminary study observed the difference in failure modes in a layered adhesive-substrate system under the same geometric conditions. Samples exhibited clear delamination behavior under quasi-static load conditions. Under these conditions,
Sylgard
®
184 showed large displacements and significant delamination with very low applied loads. In contrast, epoxy materials, SC-15 and TGDDM, produced higher shaft loads for a low displacement. These materials also exhibited delamination
behavior before a final fracture of the adhesive. To observe the dynamic load condition, samples were loaded with a shaft
velocity of 5 m/s, producing higher input loads than those measured under quasi-static conditions. For this condition,
Sylgard
®
184 showed significant resistance to delamination, and no fracture was observed. Both epoxy materials showed no
apparent delamination behavior, instead of failing due to fracture at the boundary of the substrate. These results show some
significant differences in the behavior of adhesives at different loading rates. With further improvements to sample design
and measurement systems, this is a promising technique to study these behaviors in more detail.
Acknowledgments The authors would like to thank their colleagues from the Impact Science Laboratory at Purdue University for their assistance
and support in understanding and improving this work.
References
1. Rolfe, E., Kelly, M., Arora, H., Hooper, P.A., Dear, J.P.: X-ray CT analysis after blast of composite sandwich panels. Proc. Eng. 167,
176–181 (2016)
2. Dear, J.P., Rolfe, E., Kelly, M., Arora, H., Hooper, P.A.: Blast performance of composite sandwich structures. Proc. Eng. 173, 471–478 (2017)
3. Daniel, I.M., Abot, J.L., Schubel, P.M., Luo, J.J.: Response and damage tolerance of composite sandwich structures under low velocity impact.
Exp. Mech. 52, 37–47 (2012)
4. Wan, K., Liao, K.: Measuring mechanical properties of thin flexible films by a shaft-loaded blister test. Thin Solid Films. 352, 167–172 (1999)
5. O’Brien, E.P., Case, S.L., Ward, T.C.: Critical and subcritical adhesion measurements of a model epoxy coating exposed to moisture using the
shaft-loaded blister test. J. Adhes. 81, 41–58 (2005)
Fig. 3.3 (a) Load-displacement data for quasi-static blister experiments. (b) Image from final failure of sample SC15-1 under quasi-static loading.
Point (1) denotes the boundary of the growing delamination and (2) marks the location of fracture of the adhesive. (c) Image of SC15 adhesive
failure under dynamic loading. (1) Marks the location of the ring fracture at the substrate boundary and (2) marks the location of a tensile fracture
at the location of the shaft
S. Paulson et al.