| EPSRC Reference: |
GR/R15788/01 |
| Title: |
Cohesive Modelling of Thermoplastics For Design Against Impact Fracture |
| Principal Investigator: |
Leevers, Dr P |
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| Department: |
Mechanical Engineering |
| Organisation: |
Imperial College London |
| Scheme: |
Standard Research (Pre-FEC) |
| Starts: |
01 May 2001 |
Ends: |
31 August 2004 |
Value (£): |
331,358
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| EPSRC Research Topic Classifications: |
| Materials Characterisation |
Materials testing & eng. |
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Summary on Grant Application Form |
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Impact tests are widely used to evaluate plastics -a tacit admission that even the toughest unreinforced engineering plastics can be prone to brittle failure under impact. However, twenty-five years after Fracture Mechanics succeeded in correlating impact fracture data for brittle plastics, there is still no systematic method for designing against brittle impact failures in un-notched components of tough plastics. Impact strength data cannot be applied to geometries unlike the specimen, while fracture mechanics data cannot be used for geometries which are initially un-notched. The results of this situation include unexpected failures, wastefully over-designed products, and excessive dependence on expensive fibre-reinforced plastics which are difficult to recycle.The proposed research is based on the use of new cohesive models, as an alternative to Fracture Mechanics. Material strength properties are expressed in the form of cohesive stress vs. separation relationships for internal surfaces (for polymers, craze surfaces). These properties will be measured using variants of the impact test methods which are currently emerging as ISO standards. The research will pursue strong evidence that cohesive properties can be inferred directly from bulk physical and mechanical properties, using a decohesion criterion based on adiabatic heating.Finally, the new methodology will be assessed by using it to predict impact failure in tests on simply shaped, un-notched thermoplastic components-some of which are already used as' ad hoc' test specimens.
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Key Findings |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Potential use in non-academic contexts |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Impacts |
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| Description |
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk |
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Sectors submitted by the Researcher |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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| Project URL: |
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| Further Information: |
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| Organisation Website: |
http://www.imperial.ac.uk |