1、Designation: D2343 09D2343 17Standard Test Method forTensile Properties of Glass Fiber Strands, Yarns, andRovings Used in Reinforced Plastics1This standard is issued under the fixed designation D2343; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 T
3、his test method covers the determination of the comparative tensile properties of glass fiber strands, yarns, and rovings inthe form of impregnated rod test specimens when tested under defined conditions of pretreatment, temperature, humidity, andtension testing machine speed. This test method is ap
4、plicable to continuous filament, glass fiber materials that have been coatedwith a resin compatible sizing. This method is intended for use in quality control and R or the ends shallbe sanded with 240 grit sandpaper or fine emery cloth and tested using rubber faced grips.5. Significance and Use5.1 T
5、ensile properties determined by this test method are of value for identifying and characterizing materials for control andspecification purposes as well as for providing data for research and development studies.5.2 This test method is intended for use in testing resin-compatible sized glass fiber m
6、aterials that have been designedspecifically for use with certain generic types of plastics. The use of a resin impregnantsystem that is compatible with thereinforcement material under test produces results that are most representative of the actual strength that is available in the materialwhen use
7、d as intended in an end item. Premature reinforcement failure may failures occur if the elongation of the resin systemis less than that of the reinforcement being tested. This requirement may restrict the use of certain resin systems in this procedure.Misleading results may be obtained when glass fi
8、ber materials are tested without It is critical to select a resin system that does notlead to premature reinforcement failure. Use of compatible resin system and complete resin impregnation of the fiber or when anon-compatible resin is used for impregnation.is recommended to avoid invalid failures a
9、nd misleading results.5.3 This test method is useful for testing pretreated specimens for which comparative results are desired. Values obtained bythis test method may be affected by gage Gage length, gripping system, testing speed, and the resin impregnation ratio of thespecimen.specimen affects th
10、e values obtained by this test method.6. Apparatus6.1 Impregnation ApparatusAn example of an acceptable impregnation apparatus for strands is shown in Fig. 1. Minormodifications to the apparatus are acceptable providing consistent samples are produced. The apparatus shall consist essentiallyof the f
11、ollowing:6.1.1 Free Wheeling Spindle (Optional)A freely turning spindle with a horizontal axis for holding the yarn spool or rovingball.Aspindle allows fiber to be pulled from a yarn bobbin or the outside of a roving package.Alternatively, the fiber may be drawnfrom the package without the spindle a
12、s in the case of pulling from the Alternately, inside payout or drawing of the fiber from theinterior of a roving package or forming cake.cake without the use of spindle is possible.6.1.2 Tension Regulating System capable of maintaining the roving or yarn under tension between 0.2 Newtonsnewton and
13、20Newtons.newton.1 Die 5 Moving Support2 Tensioning Bars 6 Impregnation Vat (temperature regulated)3 Resin Level 7 Glass Input4 Tensioning DeviceFIG. 1 Typical Impregnation Equipment ConfigurationD2343 1726.1.3 Impregnation Tank, as illustrated in Fig. 2, consisting of a container and a static sprea
14、der bar assembly.The tank must havethe capability of maintaining the required resin temperature within 65C. This may be accomplished by use of a double walledvat, with heating fluid circulating between the walls, or by use of an external heating plate.NOTE 3Heating and temperature maintenance may be
15、 accomplished by use of a double walled vat, with heating fluid circulating between the walls,or by use of an external heating plate.6.1.4 Die, as illustrated in Fig. 3, made of stainless steel which gives a defined circular cross-section to the impregnated roving.6.1.5 Winding Device and Framefor c
16、ollecting the impregnated roving which insures that the fibers are kept under constanttension and places the strands onto the fixture in a manner which allows separate specimens to be fabricated.6.2 Template for Tabbing (Optional)A template, as shown in Fig. 4, shall be used to provide proper positi
17、oning of end tabs.6.3 Tension Testing MachineAtesting machine having a constant-rate-of-crosshead movement and comprising essentially thefollowing shall be available:6.3.1 Stationary Member, with one grip.6.3.2 Movable Member, with a second grip.6.3.3 GripsGrips for holding the test specimen between
18、 the fixed and the movable member shall be of the self-aligning type(that is, they shall be attached to the fixed and movable members in such a manner that they will move freely into alignment assoon as any load is applied). The long axis of the test specimens will then coincide with the direction o
19、f the applied pull throughthe center line of the grip assembly.NOTE 4Air-actuated grips have been found advantageous and are recommended for use in this test method.NOTE 5Rubber with a Shore A hardness of 91 has been found to work well as a grip surface.NOTE 6Recommended starting gripping pressures
20、are 80 bars for specimens with no tabs, 60 bars for specimens with cardboard tabs, and 40 barsfor composite tabs. These may be adjusted Adjust these as necessary to prevent slippage providingprovided damage to the specimen due to crushing isprevented.6.3.4 JawsAset of removable jaws to match the req
21、uired grips shall be used for clamping the test specimens. One of the facesof the jaws shall be adjustable to compensate for thickness of the specimen ends, so that the tension force is aligned with the centerof the jaw. Rubber-faced jaws, with a gripping length of at least 50 mm, shall be used for
22、gripping specimens unless tabs are used.The jaws shall be wider than the test specimen and shall have a gripping length of at least 50 mm. Their faces shall be plane andparallel and shall ensure uniform pressure over the whole width of the test specimen to assure the specimen is held withoutslippage
23、. If slippage of the test specimens is observed, 240 grit sandpaper strips shall be used to improve gripping. The sandpapershould be replaced Replace sandpaper when it has lost its grittiness, or after every 30 to 50 breaks. Alternatively, tabbing shall beused.6.3.5 Drive MechanismA drive mechanism
24、capable of imparting a uniform controllable speed to the movable member of theapparatus.6.3.6 Load IndicatorA suitable load-indicating mechanism capable of showing the total tensile load carried by the testspecimen when held by the grips shall be used.This mechanism shall be essentially free of iner
25、tial lag at the specified rate of testingand shall indicate the load with an accuracy of at least 61 % of the indicated load value. The accuracy of the testing machine shallbe verifiable in accordance with Practices E4.6.3.7 Deflection-Measuring Device and RecorderAsuitable instrument for measuring
26、deflection (extensometer) and a suitablemechanism for recording this deflection shall be provided. It is desirable that this instrument and recorder automatically record thisdeflection as a function of the load on the test specimen. An extensometer gauge length of 50 mm is recommended.1 Entrance Gui
27、de Eye 4 Breaker Bars2 Impregnating Vat 5 Exit Tensioning Bar3 Glass Roving or Yarn 6 DieFIG. 2 Impregnation TankD2343 1736.4 Balance, Analytical.7. Test Specimens7.1 Test specimens shall consist of straight lengths of impregnated glass fiber strands, yarns, or roving. The lengths shall be atleast 2
28、50 mm.7.2 Effective Gage LengthThe distance between the tabs or the distance between the rubber faced jaws shall be 150 mm.7.3 Number of SpecimensAt least five tension test specimens shall be tested for each ball or spool of glass fiber material foreach property tested.7.4 Glass ContentThe glass con
29、tent of the impregnated glass samples shall be 70 6 5 % unless otherwise specified.8. Conditioning8.1 Strands, Yarns, and Rovings ConditioningThe glass fiber from which test specimens are to be prepared shall be kept in a room or enclosed space maintained at 23 6 2C(73.4 6 3.6F) and 50 6 10 % relati
30、ve humidity in accordance with Procedure A of Practice D618, except that 12 h shall be theminimum conditioning time.8.2 Test Specimen ConditioningThe specimens shall be conditioned and tested in a room or enclosed space maintained atatmospheric conditions of 23 6 2C (73.4 6 3.6F) and 50 6 10 % relat
31、ive humidity in accordance with Procedure A of PracticeD618, except that 16 h shall be the minimum conditioning time.9. Speed of Testing9.1 Speed of testing shall be the relative rate of motion of the grips or test fixtures during test.9.2 The standard speed of testing is 10 mm/min for tensile stren
32、gth and 5 mm/min for apparent modulus of elasticity unlessotherwise specified.10. Impregnation Procedure10.1 Set up the impregnating apparatus in accordance with Fig. 1.10.2 Cover the ends of the winding fixture using 0.025 mm (0.001 in.) nominal thickness, heat-resistant plastic film, aluminumfoil,
33、 or equivalent parting film.10.3 Prepare a sufficient quantity of an impregnantresin system suitable for impregnating the material under test. Pour theimpregnating mixture into the tank so that the level is about 10 mm (0.39 in.) above the static breaker bars (see Fig. 2).10.4 Immediately prior to t
34、hreading the material through the impregnation apparatus, cut a 1000 6 1-mm (40 6 0.04-in.) skeinof the material under test. Repeat the procedure immediately after winding one set of specimens. Place the two skeins in a mufflefurnace maintained at a temperature that will give complete burn-off (usua
35、lly 450C for 2 h) . h). Remove the two skeins fromthe furnace and place in a desiccator for a minimum of 15 min. Weigh the two skeins to the nearest 0.001 g and record as WeightX.10.5 Select a stripper die of the proper diameter by using the chart or calculations in 12.3.10.6 Thread the glass fiber
36、material through the impregnating apparatus in an “under, over, under” path through the staticspreader bars. Firmly attach the end of the glass fiber to the winding fixture with heat-resistant masking tape. Drape the materialon the winding fixture. Rotate the fixture either manually or at a motorize
37、d rate not exceeding 8 m/min (26 ft/min).FIG. 3 Guide Pulley and Impregnation TankD2343 17410.6.1 Maintain an impregnant-to-glassa resin-to-glass weight ratio of 70 % for the preparation of the test specimens (see Note7).NOTE 7The choice of die and the tex of the fiber will determine the glass conte
38、nt. It may also be affected by the content and is also influenced byviscosity of the resin used. Use the calculations in 12.2 to determine the die size to be used. If the calculated die size does not yield the needed glass-weightratio, then adjustment of the die diameter will be needed.10.6.2 After
39、the required number of specimens are wound, hold the winding tension on the material and use heat-resistantmasking tape to attach the material to the winding fixture. Cut the material after attachment has been made.NOTE 8Optionally, a flat tongue depressor or metal spatula may be used to flatten the
40、 end 100 mm (3.9 in.) of the glass strands. This flattening ofthe gripped portion of the strands allows better clamping of the specimens while minimizing crushing in the grip jaws.10.6.3 Place the loaded winding fixture in a horizontal position in an air-circulating oven at a temperature and for a l
41、ength oftime necessary to cure the resin per manufacturersmanufacturers instructions.After curing, cool to room temperature and removethe specimens from the winding fixture.10.7 Cut the specimens to the required length. Exercise care to prevent damage to the specimens during handling.10.8 Select spe
42、cimens for the test on the basis of their uniformity and freedom from cuts, nicks, or other visible imperfections.Discard any unacceptable specimens. Weigh each specimen selected to the nearest 0.001 g and record as Weight Y.NOTE 9A thorough wetting of the glass fiber is essential to obtaining accep
43、table specimens. It is important that the specimens be examined visuallyto ensure that good wet-out of the fibers by the resin has occurred. If acceptable wet out is not obtained, it shall be is necessary to adjust the configurationof the fibers through the breaker bars in the impregnation bath by c
44、hanging the over under pattern. A note regarding the quality of wet-out is requiredin the report.10.9 If tabbing is to be used, lay out the cut specimens on the template and prepare a suitable quantity of adhesive (epoxy forcardboard; polyester for mat). Place two strips of chopped strand glass fibe
45、r mat (75 mm wide) or cardboard (55 mm wide) at theirlocations on the template on a metal plate and coat them with adhesive. Place the test specimens and then apply two additionalstrips of tabbing material. Place another metal plate on top of the tabs and specimens. Place the template, tabs, specime
46、ns, and plateinto an oven and cure the tab resin at the temperature and duration recommended by the manufacturer. Upon removal from theoven, allow to cool and cut the tabbing to create individual tabbed test specimens. Take care not to damage the impregnated glassspecimens.11. Testing Procedure11.1
47、For testing tensile stress, set the speed of the testing machine at 10 mm/minute.11.2 Adjust the load scale range so that it shall be adequate for the estimated breaking load of the specimen under test.1 Notches for locations for impregnated rods 4 Dimension depending on number of specimens2 Positio
48、n for strip of cardboard or mat 5 Thickness of cardboard or mat3 Border 6 StopsFIG. 4 Tabbing TemplateD2343 17511.3 Set the jaws at the effective gage length of 150 mm 6 2 mm apart. Place the specimen in the jaws, taking care to ensurealignment of the specimen axis on the grips with an imaginary lin
49、e joining the points of the attachments of the grips to the machine.If mechanical grips are used, tighten the jaws evenly and firmly to the extent necessary to prevent slippage of the specimen duringthe test, but not to the point where the specimen is crushed.11.4 Zero the machine and start the recorder. Load the test specimen to failure. Record the ultimate breaking load.11.5 Compute the stress using the equation in 12.3.NOTE 10It is assumed for the purpose of this test that only the glass is involved in the rupturing process. This introduces a very
