1、Designation: F320 10Standard Test Method forHail Impact Resistance of Aerospace TransparentEnclosures1This standard is issued under the fixed designation F320; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revisi
2、on.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () 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 the imp
3、actresistance 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 standard. The values given in pa
4、rentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.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-pr
5、iate safety and health practices and determine the applica-bility of regulatory 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 includingscratc
6、hes, crazing, delamination, cracks, or shattering.2.1.2 ice balla frozen mass 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 b
7、allwhile in the launch tube. One type of sabot (see Fig. 1) consistsof a split 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
8、 method involves launching a series of ice ballsof specified sizes at a sample windshield at a designatedvelocity and angle and in a specified pattern. Requirements arespecified for the ice ball, test specimen, procedure, and dataacquisition. The ice ball is photographed in flight to verify itsinteg
9、rity.3.2 Requirements are specified for a particular apparatusand test procedure, but options are permitted for certain areas.However, it must be possible to demonstrate that the optionsused result in an ice ball impacting the test panel with the samesize, consistency, and velocity as with the speci
10、fied apparatusand procedure. Following are areas where options are allowed:3.2.1 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 ed
11、ition approved May 1, 2010. Published June 2010. Originallyapproved in 1978. Last previous edition approved in 2005 as F320 05. DOI:10.1520/F0320-10.FIG. 1 Sabot Configuration1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.2 Laun
12、cherAny type of launcher is allowable as longas the iceball reaches the test specimen intact at the correctspeed. 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 m
13、et.3.2.5 Test Specimen SizesThose given are minimum.3.2.6 SafetySafety must satisfy the safety standards 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
14、. By coupling this method with theinstalled angle and velocity of a specific aerospace vehicle,design 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 suitab
15、le firing rangeequipped with an ice ball mold, a launcher, blast deflector,sabot trap, velocity measuring 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 cartrid
16、ges.An example facilityis described below.5.2 Firing RangeThe firing range shall be a minimum of9 by 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
17、 waterexpansion during freezing.5.4 Launcher, any launcher may be used as noted in 3.2.2.In addition to the powder gun described in this test method,laboratories have also successfully utilized compressed gas gunlaunchers. An example of a powder gun launcher is shown inFig. 2, consisting of a barrel
18、, breech, breech plug, and control.The barrel shall be made from high-qualityAISI 4130 seamlesssteel tubing, or equivalent, in the annealed condition. Thebreech shall be made from AISI 4130 steel rod, or equivalent,heat treated to a 160- to 180-ksi (1104- to 1242-MPa) ultimatetensile strength condit
19、ion. The size of cavity to be used in thebreech depends on the desired test velocity (see Table 1). Thebreech plug, which locks the cartridge in place and contains thefiring pin, shall be made of 4340 steel heat treated to a 160- to180-ksi ultimate tensile strength condition. The firing pin isactuat
20、ed by a kinetic impact air piston. Control is accomplishedby an electrically actuated air valve. For a 100-psi (0.69-MPa)air source, a 0.75-in.2(4.84-cm2) piston traveling 0.5 in. (13mm) is used.5.5 Blast DeflectorPlace a plate with a 4-in. (100-mm)diameter hole as shown in Fig. 3 between the sabot
21、trap and thefirst velocity measuring station. Then place a corrugatedcardboard plate over the hole. This deflector is not required forcompressed gas gun systems.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
22、 6 ft (1.82 m) from the launcher muzzleas shown in Fig. 4. This trap is not required for systems thatutilize aerodynamic separation of the sabot or other suitablemechanisms to ensure that the sabot does not impact the testarticle.5.7 Velocity Measurement SystemThe break-screen veloc-ity measurement
23、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 theFIG. 2 Launcher DesignF320 102paper by the silk screen process. The paint for the circuit shallbe electronic grade electrical conducting
24、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 tobe used with the three screens. The system shall
25、 be accurate to61 % or better. Laser-based photo detector systems andhigh-speed-film-based systems may also provide the requiredaccuracy of 61%.5.8 Test Specimen HolderUse one of two types of testspecimen holders. The one in Fig. 7 is designed to hold an 18-by 18-in. (0.46- by 0.46-m) test specimen
26、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 properorientation (see 9.2).5.9 Ice Ball Integrity CameraVerify ice ball integritybefore impact by obt
27、aining 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 synchronization can be obtained byusing an open shutter with the strobe triggered at the secondvelocit
28、y 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 in view of the camera lens when the strobeis triggered.5.10 Balance, for powder and ice balls, capa
29、city 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 effective injection molded sabot configura-tion is shown in Fig. 1a, while a machined configuration is
30、shown 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 twice this diameter to assure in-flight separationof the sabot halves. An acceptable tolerance of
31、the sabotdiameter has been found to be within 0.005 in. (0.127 mm) ofthe minimum barrel diameter.6.2 GunpowderThe brands listed in Table 1 have beenfound to be satisfactory for powder guns.6.3 Cartridge Cases, with primers, 0.30 and 0.50 caliber, orother sizes may be used for powder guns.6.4 Cotton
32、FiberStandard pharmaceutical cotton balls.6.5 Bags, Polyethylene, commercial grade.6.6 Plastic WrappingPoly(vinylidene chloride).2The sole source of supply of the apparatus known to the committee at this timeis “Silver Preparation,” duPont electronic grade No. 4817. If you are aware ofalternative su
33、ppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee2, which you may attend.TABLE 1 Power LoadsDesired Veloc-ity, ft/s (m/s)Barrel Bore, in.(mm)Barrel Length,in. (m)Cartridge Si
34、ze,caliberPowder TypePowder Weight,grains (g)200 (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 Bul
35、lseye 12 (0.78)1000 (300) 0.75 (19) 10 (0.25) 0.30 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 (
36、57) 60 (1.52) 0.50 Bullseye 150 (9.72)AThe sole source 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. Y
37、our comments will receive careful consideration atameetingoftheresponsible 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 suppli
38、ers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration atameetingoftheresponsible technical committee2, which you may attendFIG. 3 Blast DeflectorF320 1037. Hazards7.1 Powder Storage and HandlingPowder handling andstorage shall confo
39、rm to all Federal and local regulations. Thehandling facility in which the powder 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 personn
40、el from the firing areaexcept the operator.7.3 Locked SwitchThere shall be a locked switch on thefiring circuit which can be closed only by a key kept in theoperators possession during the entire calibration and testprocedure.8. Test Specimen8.1 The test specimen shall be a duplicate of the windshie
41、ldbeing simulated or a section thereof. If a section is used, it shallmeasure 18 by 18 in. (0.46 by 0.46 m). Surface condition shallFIG. 4 Sabot TrapFIG. 5 Velocity ScreenFIG. 6 Velocity Measuring SystemF320 104be dry. Temperature shall be ambient unless special tempera-tures are associated with the
42、 particular installation beingsimulated. In the case of special temperatures, the temperatureto use and the method of attainment are to 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
43、 test.9. Preparation of Apparatus9.1 VelocitySelect the ice ball velocities from one of thestandard values in Table 2 unless otherwise specified.9.2 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)
44、cut section, theimpact angle shall be 45 at the center of 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
45、 and weigh an amount of cotton filler asspecified in 10.2.9.3.2 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
46、 at the lowestpoint in the mold cavity so that the rising 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 freez
47、ing by immers-ing it in room temperature water until the 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 sealed in a polyethylene bag and kept in thefreezer at 0F (18C). Ice balls shall not be more than fourdays old before use. M
48、inimize the time out of the mold becauseof the formation of cracks with time.9.4 Ice Ball Size and 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 a
49、nd five 2.0-in. (51-mm) diameter ice balls with therespective patterns shown in Fig. 8. An exception 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, impact 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 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 Fi
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