Machining and Surface Integrity Studies of Advanced composites

Composite materials and Fiber Metal Laminates are inherently prone to induced damage, both exterior as well as unseen internal damage, and both at the micro and macro length scales. This damage can result in a substantial degradation of material strength properties. The degradation typically results from every stage of the manufacturing process, from the conception of the material at the cure stage to the post-processing cutting, trimming and drilling operations performed in order to meet design allowables. This research involves a study of the typical damage induced from these various manufacturing operations on composite materials and their correlation with the strength degradation and activated failure mechanisms upon impact loading. Applications of research are primarily in the aerospace, automotive and recreational industries.

Impact Analysis of Titanium/Graphite Fiber Metal Laminate (Hybrid Composite Laminate)

Fundamental analytical investigation of the stress-fields in the cutting zone during the orthogonal cutting of FRP laminates is being conducted using the tenets of anisotropic elasticity and composite Equivalent Single Layer (ESL) theories in order to understand the physics of machining of FRPs. More realistic drilling process is also being looked into to understand the delamination phenomenon often associated with drilling the last few plies of a FRP laminate.

Environmentally Benign machining of Composites: 

Investigation of Machinability and Dust Emissions in Edge Trimming of Laminated Carbon Fiber Composites

This project involves machinability study for edge trimming and milling of carbon fiber reinforced composite laminates in terms of:

Cutting Force

• Quantify  effect of fiber orientation, tool geometry, and process conditions on cutting force
• Characterize mechanisms through cutting force measurement and analysis.
• Correlate results to surface finish and damage through measurement and analysis.
• Develop a methodology to predict cutting force.

Tool Wear

• Quantify effect of fiber orientation, tool geometry, and process conditions on tool wear.
• Characterize effect of cutting conditions through tool wear measurement and analysis.
• Correlate tool wear to surface finish and damage through measurement and analysis.
• Evaluate potential for acoustic emission sensing of tool wear through signal acquisition and analysis.

Dust Emission

• Characterize effect of fiber orientation, tool geometry, and process conditions on particles generated.
  • Particle Size (SEM)
  • Aerodynamic Diameter (Impactor)
  • Count (Ultrafine Particle Counter)
• Correlate particle size to surface finish and damage.
• Correlate particle size to tool wear.
• Provide first-ever relationship between fiber orientation, cutting conditions, and particles.