Nonlinear Viscoelastic-Viscoplastic Model Development for Strength Prediction of Bonded Joints
Abstract
Ongoing research at Clarkson University to develop a viscoelastic-viscoplastic model of composite lap joints for ship structural rel,iability has revealed that the representative adhesive system, Pro-Set ADV-176, exhibits non-linear viscoelastic behavior. Linear v,iscoelastic behavior is characterized by the stress and strain showing similar increases when either one is changed. For example, i,f the strain is doubled, the resulting stress should also double. Non-linear viscoelastic materials do not exhibit this behavior.,Characterizing the adhesive system is critical for developing a long-term prediction model of a composite lap joint that can describ,e the stress distribution and evolution within the joint. There are seven leading constitutive models for non-linear viscoelastic m,aterials: Schapery, differential, rate, Green-Rivlin, finite linear, Pipkin-Rogers, and quasi-linear. To successfully compare these, models to determine the most accurate requires cyclic loading, and experiments conducted at a range of temperatures and moisture le,vels. Further, to support the ongoing research (ONR ? BAA N00014-20-S-B001), a high volume of experiments is needed requiring testi,ng equipment with a high throughput. The necessary material testing system can be supplied by Zwick/Roell and includes a polymer mu,lti-station with environmental chamber that can test six polymer specimens simultaneously; a servohydraulic load frame with 100 kN c,apacity for cyclic loading; a 100 kN load frame with a furnace carousel to rapidly test four lap joints; and a 10 kN, low temperatur,e load frame that can test the adhesive system to low temperatures. The multi-station and the low temperature load frame are envisi,oned to test the adhesive in isolation to fully identify its material properties. The two 100 kN load frames are intended to test l,ap joint specimens to demonstrate the effects of the non-linear viscoelastic behavior on the overall lap joint performance. The res,ult will be a fullyvalidated prediction model for the service life of lap joints. The proposed cost of the material testing system i,s $1.5 million.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 04, 2022
- Source ID
- N000142312042
Entities
People
- Craig Merrett
Organizations
- Clarkson University
- Office of Naval Research
- United States Navy