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Instrumentation of Breaking Glass

Instrumentation of Breaking Glass. Strobe 6: Friday 10am–1pm strobe6@mit.edu Adam Seering aseering@mit.edu Aubrey Tatarowicz altat@mit.edu Daniel Hernandez djh@mit.edu John Hawkinson jhawk@mit.edu. How does glass break? — What ways can we instrument the cracking process?.

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Instrumentation of Breaking Glass

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  1. Instrumentation of Breaking Glass Strobe 6: Friday 10am–1pmstrobe6@mit.edu Adam Seering aseering@mit.edu Aubrey Tatarowicz altat@mit.edu Daniel Hernandez djh@mit.edu John Hawkinson jhawk@mit.edu

  2. How does glass break?— What ways can we instrument the cracking process? Concept - What we did - Results - Feasible? - Timeline

  3. Making it break! Concept - What we did - Results - Feasible? - Timeline • We tried several ways: • Heat on glass + cold water (for thermal shock) • Impact from a falling weight • BB gun • What can we measure and quantify?

  4. What we want to measure (goals) Concept - What we did - Results - Feasible? - Timeline • Is there a consistent shape to the breaking? • What is the rate and pattern of deformation and breakage? • How does glass breaking process depend on glass thickness? • Comparison of different measurement techniques • Schlieren, electrically conductive tape, video • Effects of different-shaped impact objects (screwdriver, BB, etc.) • What are the effects of temperature?

  5. Investigation of breaking by thermal shock Concept - What we did - Results - Feasible? - Timeline • 1mm thick microscope slides,clamped to lab stand • ~200°C soldering iron:did not break on instant contact • Nor did glass break on sustained contact • 380°C from heat gun • Still glass slide does not break

  6. Thermal Shock Works! Concept - What we did - Results - Feasible? - Timeline • 380°C from heat gun • Release drop of water → Whether the slide breaks depends on height of water release

  7. Lighting

  8. Investigation of glass breaking by impact Concept - What we did - Results - Feasible? - Timeline • Thicker sheets of glass —3/32" (2.4 mm) • Cut sheets to ~2"x8" • Taped across apple boxes • Dropped mass (screwdriver) from different heights

  9. Results We can measure crack motion in time Concept - What we did - Results - Feasible? - Timeline 13 μs per step

  10. ResultsWe observe flexing of glass, but want a better visuals and instrumentation. Ideas: try projecting a grid onto glass, or view glass edge-on Concept - What we did - Results - Feasible? - Timeline

  11. Lighting to get good results • Back lighting and side lighting work well in order to see cracking, these were used in the images in the previous slides • Top lighting produces a lot of glare

  12. YES! It is feasible Concept - What we did - Results - Feasible, YES! - Timeline • From the trials with slides • We can measure the speed of the crack motion • We can break with force and/or thermal shock • However, it might be hard to see deformation on slide since they are so small • From the thick sheets, • We can see glass flexing upon impact of blunt object • The shattering is more defined — will probably yield better results than the slides

  13. Cost is cheap! Concept - What we did - Results - Feasible, YES! - Timeline • One 8"x10" sheet of glass costs $2 • Cut into five 2“ inch slices → $0.40 per slice • Box of slides costs $8 (72 slides) • $0.11 per slide

  14. Future direction Concept - What we did - Results - Feasible, YES! - Timeline • Thicker sheets are more exciting than small slides: need to reproduce thermal shock using sheets. • We want to try different lighting techniques and camera angles since these factors will be key in being able to extract useful data.

  15. Timeline Concept - What we did - Results - Feasible, YES! - Timeline

  16. Instrumentation of Breaking Glass Strobe 6: Friday 10am–1pmstrobe6@mit.edu Adam Seering aseering@mit.edu Aubrey Tatarowicz altat@mit.edu Daniel Hernandez djh@mit.edu John Hawkinson jhawk@mit.edu

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