Energy transport mechanisms and their impact on the matrix damage during pulsed laser processing of carbon fiber reinforced plastics

• Applicant: Professor Dr. Thomas Graf
• Subject Area: Production Automation and Assembly Technology
• Term: from 2015 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 262128969

The strongly inhomogeneous structure of carbon fiber reinforced plastics (CFRP) facilitates thermal damaging of the material and therefore implies particular difficulties for laser materials processing of this material. A major cause for the thermal damage is the good heat conductivity along the carbon fibers. Heat flows from the interaction zone into the compound where it causes matrix damage. However, this is not the only mechanism which leads to thermal damage of the CFRP compound. Other energy redistribution mechanisms such as reflection of laser radiation at the round cross section of the carbon fibers, hot ablation products and oxidation also influence the thermal damaging of the material. In the frame of this project the physical processes which influence the insertion and redistribution of the incoming energy during pulsed laser processing of CFRP will be quantified. It is planned to consider the following effects:(i) Heat accumulation effect in the case of heat conducting along the carbon fibers into the compound;(ii) Reflection of laser radiation during laser processing due to the inhomogeneous material structure;(iii) Heat transport due to the expansion of hot vapor / plasma;(iv) Additional energy input and influences on ablation due to oxidation of the material.Most of these effects do not occur solely during the processing of CFRP but they become especially evident in this case because of the inhomogeneous structure of the material. Therefore an experimental and theoretical distinction and quantification of the different effects becomes possible.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Foundation for Basic Research
• Participating Person: Dr. Vitaly Konovkonov