FORD FLTM BZ 107-01-2016 LAMINATED GLASS RESISTANCE TO LEADING SIMULATED STONE IMPACT TESTING.pdf

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1、 FORD LABORATORY TEST METHOD BZ 107-01 Date Action Revisions Rev. 0 2016 08 09 Released R. Surowiec, P. Konopka, NA Controlled document at www.MATS Copyright 2016, Ford Global Technologies, LLC Page 1 of 6 LAMINATED GLASS RESISTANCE TO LEADING SIMULATED STONE IMPACT TESTING Application This test pro

2、cedure assesses the resistance of a laminate (typically a windshield or windscreen) to develop long cracks resulting from flaws caused by stone impact. Stone impact is simulated using steel ball bearings (BBs) discharged at typical highway speed from a device here called a “BB Impact Tester”. Chemic

3、als, materials, parts, and equipment referenced in this document must be used and handled properly conforming to regional firearms legislation and health and safety requirements. Apparatus and Materials Required Test Stand The laminate shall be mounted vertically and the BB Impact Tester oriented so

4、 that the BB strikes the surface at 45. The laminate shall be supported at its bottom quarter points and leaning back 10 2, as illustrated in Figure 1. Figure 1 - Stone impact test support at the quarter points. The surface of the laminate must not be loaded with a force that would create tension on

5、 the surface. Regulated air source The BB Impact Tester requires a regulated 0 to 90 PSI (0 to 0.6 MPa) maximum dry air source with 4 CFM (100 l/m) minimum flow. The air pressure determines the speed the BB is discharged at. A digital air pressure regulator provides the best speed repeatability. BB

6、Impact Tester The direction of impact shall be at a 45 angle to the surface of the laminate. Chronograph or equivalent for measuring speed of impact. See Figure 2 for the Ford BB Impact Tester with a 45 impact angle and built-in chronograph. FORD LABORATORY TEST METHOD BZ 107-01 Copyright 2016, Ford

7、 Global Technologies, LLC Page 2of 6 Figure 2 - Ford BB Impact Tester with built-in chronometer, CAD assembly number 976-529-0 BB 0.25 0.0001 inch, (6.35 0.0025 mm) BBs, approximately 1.0 gram mass. E52100 Alloy Steel, ball hardness within a range of HRC 60 67. It is essential that the BBs be free o

8、f surface particles of any kind or size. The BBs shall be washed with isopropyl alcohol and dried between paper wipes prior to each use. BBs with glass chips adhered to its surface will cause a high damage rate. Use an appropriate solvent to remove any oils, grease, or other contaminants on the BBs

9、surface. The BB can be reused as often one desires provided there are no flat spots or obvious surface flaws. Ruler or circle template, millimeters Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere of 23 +/- 2 C and 50 +/-

10、5 % relative humidity for not less than 4 h prior to testing and tested under the same conditions, unless otherwise specified. Clean the laminate outer surface. It is essential that the glass surface is free of dust and particles of any kind. Glass chips will cause a high damage rate. Procedure Two

11、test procedures are described. Each procedure has its advantages. The Variable Velocity procedure provides the best statistics, can be applied to any glass construction, but takes twice as long to perform. The Fixed Velocity procedure is quicker to perform but is only valid if impact damage occurs.

12、Without impact damage one cant tell if long leads will form. Typically, the Fixed Velocity procedure would be used as a quick method to verify a laminate design and to meet a minimum requirement. FORD LABORATORY TEST METHOD BZ 107-01 Copyright 2016, Ford Global Technologies, LLC Page 3of 6 Fixed Vel

13、ocity Procedure Impact locations are to be between 125 and 300 mm apart and spaced on an approximately uniform grid. Circle approximate impact locations with a permanent marker. On windshields, there shall be a minimum of 15 impact locations equally spaced throughout the clear region of the laminate

14、 and 10 impact locations in an area 15 to 25 mm from the glass edge (3 impact locations evenly spaced along roof and cowl edges, 2 along each pillar edge). If the part has a dark ceramic frit perimeter, the impact must occur in the ceramic area. The impact location design for windshields is illustra

15、ted in Figure 3. Impact locations for other laminates can mimic the windshield layout or use a uniform grid pattern as indicated in 1). The total number of impact sites will depend on the laminate size. Figure 3 - Stone impact test locations Unless specified otherwise, the speed of the BB is to be 2

16、91 m/s (652 mph) for the clear region. The speed of impact is to be 201 m/s (452 mph) for impact locations over the ceramic frit region. Variable Velocity Procedure Based on Staircase Testing Ideally, the staircase procedure requires equal up and down increments. The BB Impact Tester speed is nonlin

17、ear with air pressure so the speed adjustments will be approximate. To simulate the up and down increments, the impact speed shall be adjusted in approximately 5 mph (2.2 m/s) increments by incrementing the air pressure a fixed amount that will generate approximately 5 mph (2.2 m/s) speed change at

18、60 mph (27 m/s). If mean threshold break speed is not known, start with 271 m/s (602 mph) for the clear region and 151 m/s (352 mph) over the ceramic frit region. 1) Impact locations are to be no closer than 125 mm apart. 2) Mark each undamaged impact so a given site is not reused. Each impact shall

19、 be on a fresh site. 3) For best practice, a random impact order is required. Do not start at the same position with every windshield. 4) If no breakage occurs on an impact, increase the air pressure for the next impact. If breakage occurs, decrease the air pressure for the next impact. 5) To track

20、test progression, use the notation “Support” and “Break” (“S” and “B”, where “S” indicates the glass supported the impact without any damage and “B” means the glass was damaged). 6) Attempt to get at least 3 support-break thresholds per region, more would be better. 7) When all locations in the clea

21、r region have been tested, repeat the procedure in the ceramic frit region along the perimeter. 8) After all laminates have been tested, use Minitab to compute an average threshold break speed and standard deviation for each region. 9) Report the Minitab results (means and standard deviations) for b

22、oth the clear and ceramic regions, and evaluation results. FORD LABORATORY TEST METHOD BZ 107-01 Copyright 2016, Ford Global Technologies, LLC Page 4of 6 Staircase Minitab Analysis Procedure Use Minitab Accelerated Life Testing, the example below uses data collected from six windshields. 1) Enter im

23、pact speed in column C1, see Figure 4 for MPH example 2) Enter either 0 for Support (“S”) or 1 for Break (“B”) under column C2 for corresponding speed value 3) Under Stat menu, select “Reliability/Survival” and then “Distribution Analysis Plot-Right Censoring, Distribution Overview” 4) Under Variabl

24、es Window, type “C1”, see Figure 5 5) Under Parametric analysis Distribution, select “Lognormal” 6) Click the Censor button 7) Select “Use censoring columns:” 8) In window below “Use censoring columns” enter “C2” 9) In the Censoring Value Box, enter “1” 10) Click OK. 11) Click OK. Minitab will gener

25、ate a report, which includes a chart. 12) Report the Mean and StDev values. 13) Store the Minitab report, Figure 6. Figure 4 Minitab Worksheet Example of six windshields. C1 and C2 are stacked data from C4-C15 FORD LABORATORY TEST METHOD BZ 107-01 Copyright 2016, Ford Global Technologies, LLC Page 5

26、of 6 Figure 5 Minitab options Figure 6 - Example MPH impact speed results using Figure 3 data FORD LABORATORY TEST METHOD BZ 107-01 Copyright 2016, Ford Global Technologies, LLC Page 6of 6 Evaluation Record the type of damage at the impact location. Note any damage that develops into cracks within approximately 5 s after impact. Types of damage (see Figure 7) are: No damage, Crush, Starburst, Cone and Crack. Record the minimum diameter of a circle into which all damage from one point will fit. See Figure 7. Figure 7 Type of damage examples, and diameters greater and less than 50mm.