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C. Gabry, A. Mapelli , P. Renaud

Investigation of the structural resistance of Silicon membranes for microfluidic applications in High Energy Physics. C. Gabry, A. Mapelli , P. Renaud. Summary. Objectives of the project List of possible test methods Next tasks Search for available tools. Objectives.

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C. Gabry, A. Mapelli , P. Renaud

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  1. Investigation of the structural resistance of Silicon membranes for microfluidic applications in High Energy Physics C. Gabry, A. Mapelli, P. Renaud

  2. Summary • Objectives of the project • List of possible test methods • Next tasks • Search for available tools

  3. Objectives • Implement test method to determine Single Crystal Silicon (SCSi) fracture toughness • Fabrication & test of specimens • Comparison of obtained results with FEA

  4. Possible test methods • Micro-indentation • Compact Tests / Double Cantilever Beam • Compression Loaded Double Cantilever Beam • Three/four point bending • Other (cantilever bending, On-chip tensile test device)

  5. Micro-indentation Easy to implement Possible to test several crystalline orientations Machinery quite common Measuring the crack length Residual stress after indentation Hard to simulate with FEA

  6. Compact Tests Less plastic deformation in thick arms Short arms => crack growth direction more controllable Plastic deformation & parasitic crack growth at load pins Only initiation Tensile load applied

  7. Double Cantilever Beam Theoretically possible to measure propagation values Plastic deformation in arms Direction of crack growth Tensile load applied

  8. Compression-Loaded Double Cantilever Beam No tensile stress applied Side groove to help crack grow in the intended direction Stable crack growth Crack growth monitored with thin film resistance Wrong direction of crack growth Hard to test such specimens (need a frame to hold them)

  9. Three/four point bending ASTM standard procedures available Test under bending conditions Standard nor adapted to our needs (scale) No propagation measurements

  10. Three/four point bending General calculations led to the following conclusions : Specimen size : B = 1 mm (thickness) W = 0.75 mm (width) L = 6.75 mm (length) a = 0.375 mm (crack length) Fc ≈ 5 N (critical fracture force) yc ≈ 1 um (deformation at fracture)

  11. Other On chip tensile test device : Complicated analysis Sharpness of notch

  12. Other Microcantilever beams : Not a fracture test ! (no notch)

  13. Next tasks • Find available machinery • Estimate feasibility of each method depending of available machinery • Design/fabrication of chosen specimen • Testing of specimen & analysis of results • Comparison with FEA • Test several methods/geometries to get broader range of results

  14. Program

  15. Find available machinery • Meeting with H. Shea 18 mars(contact ✔; answer✔) • Contact C. Ballif (Pvlab, EPFL) (contact ✔; answer✗) • Contact Tobias Bandi (CSEM), who performs fracture toughness tests on SCSi (H. Shea) (contact ✔; answer✗) • Genova : Nano-indenter & tensile test machine (contact ✗; answer✔) • See at CERN what is available with StephanoSgobba(contact ✗; answer✗) • Contact W. Dufour (laboratoire de métallurgiemécanique, EPFL)(contact ✔; answer✔) • Contact Cmi at EPFL(contact ✗; answer✗) • Contact IMX (institut des matériaux) at EPFL(contact ✔; answer✗)

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