WINDOW TESTING NEWS

zTested window 3 yused “perfected” system ybroke at predicted pressure yFEA successes/ FEA problems zPlans ynew discovery yuse photogrammetry to measure thickness

Improvements made Increased information in central regions Increased stability of system yProjector yCamera (tripod, remote shutter) yPressurization system

Payoff from improvements X rms, Y rms, Z rms ~ 5 um

WINDOW TESTING NEWS zTested window 3 yused “perfected” system ybroke at predicted pressure yFEA successes/ FEA problems zPlans ynew discovery yuse photogrammetry to measure thickness

Burst pressure

Equipment protection

Video camera Video camera

Information from video 1/30 second - a few drops on shield + 1/30 second - hear & see tear ……..cannot see where tear began

WINDOW TESTING NEWS zTested window 3 yused “perfected” system ybroke at predicted pressure yFEA successes/ FEA problems zPlans ynew discovery yuse photogrammetry to measure thickness

FEA success Window 1

FEA problems zWindow 1 has the correct geometry in the FEA model. yFEA deflection = measured deflection zWindow 2 & 3 incorrect geometry input to FEA yFEA deflection > measured deflections yWindow is thicker than input geometry indicated, hence under- estimated true stiffness

WINDOW TESTING NEWS zTested window 3 yused “perfected” system ybroke at predicted pressure yFEA successes/ FEA problems zPlans ynew discovery yuse photogrammetry to measure thickness

Newest discovery Periodic variation observed in deflection as f(azimuth) may be an indication of harmonic variations in the circumferential direction.

Newest discovery zAt the crown end where the crown radius is forced to join the knuckle, known as the junction of discontinuity, compressive stress will develop in order that the two new radii can join up. zTo allow the dissipation of this compressive stress, the knuckle will develop a number of this wrinkles, or ripples, around its circumference. The number of ripples depends of the magnitude of the compressive stress. 4 is the starting point, hence the term harmonic 4. zAs the rest of the crown is relatively thin, the presence of these ripples, normally in micron level, suddenly become significant. Because of this, it allows these ripples to extend from the knuckle region to the rest of the crown towards its center. zAs the pressure builds up, the crown stretches out more, like an inflated balloon, thereby counter balancing the effect of these ripples, similar to the straightening of a fold line. This is why we see less and less of the harmonic effect at the crown center as the pressure builds up.

Explanation of compressive forces in torispherical endcap Rr Deformed shape of the different pressure envelope under a uniform pressure Shape of the original pressure envelope Discontinuity between the 2 radii which causes compressive stresses Tensile stresses R >> r

Newest discovery zUse a 3-D model with fine enough mesh to cover the knuckle region so that it can compute the expected compressive stress (will take 3-5 days to run FEA) zThis static harmonic variation can be represented by a Fourier series if one can work out the magnitude of the coefficients a 0, a 1, a 2 ….a n and b 0, b 1, b 2, ….b n etc.

WINDOW TESTING NEWS zTested window 3 yused “perfected” system ybroke at predicted pressure yFEA successes/ FEA problems zPlans ynew discovery yuse photogrammetry to measure thickness

Window thickness from photogrammetry zPlan to measure window thickness using photogrammetry (currently use CMM) zProcedure: perform photogrammetric measurements on both sides of the window.

Photogrammetry setup for thickness measurement

Window thickness from photogrammetry front back

Window thickness from phothogrammetry front/back

Thickness calculation zUse VANGO to create a surface model zVANGO is CADD software for land development civil engr and surveying zVANGO evolved from Van Dell CO GO zCO GO = coordinate geometry

Check Met-L-Chek zMet-L-Chek : Fluorescent and Visible Dye Penetrant Inspection Materials zMet-L-Chek = beads in matrix of isopropyl alcohol zRecently learned beads can be as large as 15um (previously thought beads were sub-micron) zMeasure effect of thickness of Met-L-Chek