1、Designation: F 320 05Standard Test Method forHail Impact Resistance of Aerospace TransparentEnclosures1This standard is issued under the fixed designation F 320; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method covers the determination of
3、the impactresistance of an aerospace transparent enclosure, hereinaftercalled windshield, during hailstorm conditions using simulatedhailstones consisting of ice balls molded under tightly con-trolled conditions.1.2 The values stated in inch-pound units are to be regardedas the standard. The values
4、given in parentheses are forinformation only.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regula
5、tory limitations prior to use. For specific hazardstatements see Section 7.2. Terminology2.1 Definitions:2.1.1 damageany modification in visual properties orintegrity of a windshield as a result of hail impact includingscratches, crazing, delamination, cracks, or shattering.2.1.2 ice balla frozen ma
6、ss of water, with filler, thatsimulates a natural hailstone in weight, size, and toughness.2.1.3 impact anglethe angle between the ice ball flightpath and the target normal.2.1.4 sabota plastic device for protecting the ice ballwhile in the launch tube. One type of sabot (see Fig. 1) consistsof a sp
7、lit polycarbonate rod containing a central cavity forholding the ice ball. Each sabot half is designed to assureaerodynamic separation from the ice ball after ejection fromthe launch tube.3. Summary of Test Method3.1 The test method involves launching a series of ice ballsof specified sizes at a sam
8、ple windshield at a particular velocityand angle and in a specified pattern. Requirements are specifiedfor the ice ball, test specimen, procedure, and data acquisition.The ice ball is photographed in flight to verify its integrity.3.2 Requirements are specified for a particular apparatusand test pro
9、cedure, but options are permitted for certain areas.However, it must be possible to demonstrate that the optionsused result in an ice ball at the test panel with the same size,consistency, and velocity as with the specified apparatus andprocedure. Following are areas where options are allowed:3.2.1
10、Ice Ball Mold Material.1This test method is under the jurisdiction of ASTM Committee F07 onAerospace and Aircraft and is the direct responsibility of Subcommittee F07.08 onTransparent Enclosures and Materials.Current edition approved Mar. 1, 2005. Published March 2005. Originallyapproved in 1978. La
11、st previous edition approved in 1999 as F 320 94 (1999).FIG. 1 Sabot Configuration1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.2 LauncherAny type of launcher is allowable as longas the iceball reaches the test specimen at the
12、correct speed.The use of sabots and sabot material and geometry areoptional.3.2.3 Method of Determining Ice Ball Integrity.3.2.4 Ice Ball Speed Measurement, Optional as long asaccuracy standards are met.3.2.5 Test Specimen SizesThose given are minimum.3.2.6 SafetySafety must satisfy the safety stand
13、ards of thetest facility being used.4. Significance and Use4.1 This test method may be used to determine the hailimpact resistance of windshields for acceptance, design, ser-vice, or research purposes. By coupling this method with theinstalled angle and velocity of a specific aerospace vehicle,desig
14、n allowables, criteria, and tolerances can be establishedfor that vehicles windshield.5. Apparatus5.1 The facilities and equipment required for the perfor-mance of this test procedure include a suitable firing rangeequipped with an ice ball mold, a launcher, blast deflector,sabot trap, velocity meas
15、uring system, test specimen holder,and a camera with strobe lights to verify ice ball integrity.Ancillary equipment required for this test include test speci-men, ice balls, sabots, and firing cartridges.An example facilityis described below.5.2 Firing RangeThe firing range shall be a minimum of9 by
16、 18 ft (3 by 6 m) enclosed to contain flying debris and toexclude unauthorized personnel.5.3 Ice Ball Mold, two aluminum blocks with hemisphericalcavities and vent holes for filling with water and for waterexpansion during freezing.5.4 Launcher, shown in Fig. 2, consists of a barrel, breech,breech p
17、lug, and control. The barrel shall be made fromhigh-quality AISI 4130 seamless steel tubing, or equivalent, inthe annealed condition. The breech shall be made from AISI4130 steel rod, or equivalent, heat treated to a 160- to 180-ksi(1104- to 1242-MPa) ultimate tensile strength condition. Thesize of
18、cavity to be used in the breech depends on the desiredtest velocity (see Table 1). The breech plug, which locks thecartridge in place and contains the firing pin, shall be made of4340 steel heat treated to a 160- to 180-ksi ultimate tensilestrength condition. The firing pin is actuated by a kinetici
19、mpact air piston. Control is accomplished by an electricallyactuated air valve. For a 100-psi (0.69-MPa) air source, a0.75-in.2(4.84-cm2) piston traveling 0.5 in. (13 mm) is used.5.5 Blast DeflectorPlace a plate with a 4-in. (100-mm)diameter hole as shown in Fig. 3 between the sabot trap and thefirs
20、t velocity measuring station. Then place a corrugatedcardboard plate over the hole.5.6 Sabot Trap is made by placing two steel plates two tofour ice ball diameters apart, centered on the flight path andlocated a minimum of 6 ft (1.82 m) from the launcher muzzleas shown in Fig. 4.5.7 Velocity Measure
21、ment SystemThe break-screen veloc-ity measurement consists of a set of screens, power supply,wiring, and counters. Three screens shall be made from alightweight bond paper with an electrical circuit painted on thepaper by the silk screen process. The paint for the circuit shallbe electronic grade el
22、ectrical conducting paint.2Do not thin thepaint. The break-screen shall be made with lines18 in. (3.2mm) wide by 18 in. (460 mm) long as shown in Fig. 5 givinga resistance of no more than 300 V. Fig. 6 shows thearrangement of components and gives the electronic circuit to2The sole source of supply o
23、f the apparatus known to the committee at this timeis “Silver Preparation,” duPont electronic grade No. 4817. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible t
24、echnical committee2, which you may attend.FIG. 2 Launcher DesignF320052be used with the three screens. The system shall be accurate to61 % or better. Laser-based and high-speed-film-based sys-tems may also provide the required accuracy of 61%.5.8 Test Specimen HolderUse one of two types of testspeci
25、men holders. The one in Fig. 7 is designed to hold an 18-by 18-in. (0.46- by 0.46-m) test specimen that can be impactedat angles ranging from 0 to 80 as detailed in Section 8. Whentesting a complete windshield, use edge restraints similar to theactual installation and place the windshield in the pro
26、perorientation (see 9.2).5.9 Ice Ball Integrity CameraVerify ice ball integritybefore impact by obtaining a photograph of the ice ball in flightbefore impact. This may be accomplished by illuminating theice ball with a strobe light while the ice ball is in the field ofview of a camera lens. This syn
27、chronization can be obtained byusing an open shutter with the strobe triggered at the secondvelocity screen. The signal is split with part going to thevelocity counters and part to a variable time-delay generator.Using the estimated ice ball velocity, a time delay is selected sothe ice ball will be
28、in view of the camera lens when the strobeis triggered.5.10 Balance, for powder and ice balls, capacity 0.2 lb (100g), accuracy 61 % (1.0 g).5.11 Clinometer or Protractor, to measure impact angle,accuracy 614 .5.12 Syringe, 100-cm3, for putting water into the ice ballmold.6. Materials6.1 SabotAn eff
29、ective injection molded sabot configura-tion is shown in Fig. 1a, while a machined configuration isshown in Fig. 1 b. In either design, polycarbonate material isused to form the two halves of the sabot at a minimum diameterequal to the ice ball diameter plus18 in. (3.2 mm) with a lengthapproximately
30、 twice this diameter to assure in-flight separationof the sabot halves. Tolerance of the sabot diameter shall bewithin 0.005 in. (0.127 mm) of the minimum barrel diameter.6.2 GunpowderThe brands listed in Table 1 have beenfound to be satisfactory.6.3 Cartridge Cases, with primers, 0.30 and 0.50 cali
31、ber.6.4 Cotton FiberStandard pharmaceutical cotton balls.6.5 Bags, Polyethylene, commercial grade.6.6 Plastic WrappingPoly(vinylidene chloride).7. Hazards7.1 Powder Storage and HandlingPowder handling andstorage shall conform to all Federal and local regulations. Thehandling facility in which the po
32、wder charges are weighed andloaded must be reserved for this purpose alone. Procureprimers already mounted in the cartridge cases or specialfacilities provided for this dangerous operation.7.2 Firing AreaExclude all personnel from the firing areaexcept the operator.7.3 Locked SwitchThere shall be a
33、locked switch on thefiring circuit which can be closed only by a key kept in theoperators possession during the entire calibration and testprocedure.TABLE 1 Power LoadsDesired Veloc-ity, ft/s (m/s)Barrel Bore, in.(mm)Barrel Length,in. (m)Cartridge Size,caliberPowder TypePowder Weight,grains (g)200 (
34、60) 1.25 (32) 10 (0.25) 0.30 BullseyeA6 (0.39)2.25 (57) 10 (0.25) 0.30 Bullseye 6 (0.39)500 (150) 0.75 (19) 10 (0.25) 0.30 Bullseye 5 (0.32)1.25 (32) 60 (1.52) 0.50 4227B40 (2.59)2.25 (57) 60 (1.52) 0.50 Bullseye 30 (1.94)2.25 (57) 10 (0.25) 0.30 Bullseye 12 (0.78)1000 (300) 0.75 (19) 10 (0.25) 0.30
35、 Bullseye 9 (0.58)1.25 (32) 60 (1.52) 0.50 Bullseye 60 (3.89)1.25 (32) 10 (0.25) 0.30 Bullseye 20 (1.30)2.25 (57) 60 (1.52) 0.50 Bullseye 70 (4.54)2000 (600) 0.75 (19) 60 (1.52) 0.50 Bullseye 35 (2.27)1.25 (32) 60 (1.52) 0.50 Bullseye 70 (4.54)2.25 (57) 60 (1.52) 0.50 Bullseye 150 (9.72)AThe sole so
36、urce of supply of the apparatus known to the committee at this time is Hercules, Inc., 1313 North Market Street Wilmington, DE 19894-0001. If you are awareof alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at
37、ameetingoftheresponsible technical committee2, which you may attendBThe sole source of supply of the apparatus known to the committee at this time is duPont, Chestnut Run Plaza 705/GS38 Wilmington, DE 19880-0705. If you are awareof alternative suppliers, please provide this information to ASTM Inter
38、national Headquarters. Your comments will receive careful consideration atameetingoftheresponsible technical committee2, which you may attendFIG. 3 Blast DeflectorF3200538. Test Specimen8.1 The test specimen shall be a duplicate of the windshieldbeing simulated or a section thereof. If a section is
39、used, it shallmeasure 18 by 18 in. (0.46 by 0.46 m). Surface condition shallbe dry. Temperature shall be ambient unless special tempera-tures are associated with the particular installation beingsimulated. In the case of special temperatures, the temperatureto use and the method of attainment are to
40、 be established bymutual agreement between the user and the testing agency. Usea strong backlight to aid visual inspection of the windshieldboth before and after the test.9. Preparation of Apparatus9.1 VelocitySelect the ice ball velocities from one of thestandard values in Table 2 unless otherwise
41、specified.FIG. 4 Sabot TrapFIG. 5 Velocity ScreenFIG. 6 Velocity Measuring SystemF3200549.2 Impact AngleSelect the impact angles from the fol-lowing standard conditions, unless otherwise specified.9.2.1 For the 18- by 18-in. (0.46- by 0.46-m) cut section, theimpact angle shall be 45 at the center of
42、 the section.9.2.2 For the complete windshield, the impact angle at thecenter and at the edge shall be the actual minimum anglebetween the ice ball flight path and the normal to thewindshield surface.9.3 Preparation of Ice Balls:9.3.1 Separate and weigh an amount of cotton filler asspecified in 10.2
43、.9.3.2 Dip the above amount of cotton into a container ofwater, remove, and shape into a sphere.9.3.3 Place the cotton sphere into the mold.9.3.4 After securing the mold halves, fill the cavity withwater from a syringe. Place the syringe point at the lowestpoint in the mold cavity so that the rising
44、 water will drive theair out.9.3.5 Place the mold in a 0F (18C) environment untilfrozen. With experience, complete freezing can be determinedfrom the length of the sprue extruded from the filler hole.9.3.6 Rapidly bring the mold to above freezing by immers-ing it in room temperature water until the
45、ice on the mold slips.Remove from water.9.3.7 Open the mold and remove the ice ball. At this point,the ice ball may be placed in a polyethylene bag and kept in thefreezer at 0F (18C) for a few hours. Minimize the time outof the mold because of the formation of cracks with time.9.4 Ice Ball Size and
46、Impact Pattern:9.4.1 If a pass/fail iceball size requirement is not specified,impact nine12-in. (13-mm) diameter ice balls in the patternshown in Fig. 8. Likewise, impact nine 1.0-in. (25-mm)diameter and five 2.0-in. (51-mm) diameter ice balls with therespective patterns shown in Fig. 8. An exceptio
47、n is the testingof a windshield edge where only four 2.0-in. (51-mm) ice ballswill be tested. If a pass/fail iceball size requirement isspecified, imapct with the specified iceball size in the Fig. 8pattern, which is nearest to the specified size.9.4.2 Orient the edge of the windshield such that the
48、 centerof the impact pattern is located 2.8 in. (71 mm) laterally fromthe point on the windshield edge selected in 9.2.2. Thisorientation is shown in Fig. 9 for a 2.0-in. (51-mm) diameterice ball impact test. Any impact points that would fall outsideof the windshield area will be omitted.9.5 Test Sp
49、ecimenIn addition to the requirements ofSection 8, mark the test specimen at the desired location for thefirst impact points and mount in the test specimen holder at theproper angle (see 9.2).9.6 Velocity ScreensPrepare velocity screens as describedin 5.6. Use three screens per shot.9.7 CartridgeLoad an appropriate number of cartridgeswith the amounts of gunpowder based on the calibration tests(see 10.1).10. Calibration and Standardization10.1 Calibration of Powder ChargesCalibrate the chargebefore testing within 10 % of the planned velocity.Acc
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