1、Designation: D 905 08Standard Test Method forStrength Properties of Adhesive Bonds in Shear byCompression Loading1This standard is issued under the fixed designation D 905; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f 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 Department of Defense.INTRODUCTIONThe accuracy of the results of stre
3、ngth tests of adhesive bonds will depend on the conditions underwhich the bonding process is carried out. Unless otherwise agreed upon by the manufacturer and thepurchaser, the bonding conditions shall be prescribed by the manufacturer of the adhesive. In order toensure that complete information is
4、available to the individual conducting the tests, the manufacturerof the adhesive shall furnish numerical values and other specific information for each of the followingvariables:(1) The moisture content of the wood at the time of bonding.(2) Complete mixing directions for the adhesive.(3) Condition
5、s for applications of the adhesive including the rate of spread or thickness of film,number of coats to be applied, whether to be applied to one or both surfaces, and the conditions ofdrying where more than one coat is required.(4) Assembly conditions before application of pressure, including the ro
6、om temperature, length oftime, and whether open or closed assembly is to be used.(5) Curing conditions, including the amount of pressure to be applied, the length of time underpressure and the temperature of assembly when under pressure. It should be stated whether thistemperature is that of the bon
7、d line, or of the atmosphere at which the assembly is to be maintained.(6) Conditioning procedure before testing, unless a standard procedure is specified, including thelength of time, temperature, and relative humidity.Arange may be prescribed for any variable by the manufacturer of the adhesive if
8、 it can be assumedby the test operator that any arbitrarily chosen value within such a range or any combination of suchvalues for several variables will be acceptable to both the manufacturer and the purchaser of theadhesive.1. Scope1.1 This test method covers the determination of the com-parative s
9、hear strengths of adhesive bonds used for bondingwood and other similar materials, when tested on a standardspecimen under specified conditions of preparation, condition-ing, and loading in compression. This test method is intendedprimarily as an evaluation of adhesives for wood.1.2 The values state
10、d in SI units are to be regarded as thestandard. The values given in brackets are provided forinformation purposes 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-pr
11、iate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 143 Test Methods for Small Clear Specimens of TimberD 907 Terminology of AdhesivesD 5266 Practice for Estimating the Percentage of Wood1This test meth
12、od is under the jurisdiction of ASTM Committee D14 onAdhesives and is the direct responsibility of Subcommittee D14.30 on WoodAdhesives.Current edition approved Oct. 1, 2008. Published October 2008. Originallyapproved in 1947. Last previous edition approved in 2003 as D 905 03.2For referenced ASTM s
13、tandards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocke
14、n, PA 19428-2959, United States.Failure in Adhesive Bonded Joints3. Terminology3.1 DefinitionsMany terms in this test method are definedin Terminology D 907.4. Significance and Use4.1 It cannot be assumed that this test method measures thetrue shear strength of the adhesive bond. Many factors interf
15、ereor bias the measurement including the strength of the wood, thespecimen, the shear tool designs themselves, and the rate ofloading.4.1.1 Wood failure is very common in joints made withstrong adhesives. Although high wood failure is normallydesired, when it occurs the measured strength is lower th
16、an thetrue adhesive bond strength.4.1.2 Stress concentrations at the notches of the specimentend to lower the measured strength. In a similar test for theshear strength of solid wood, Test Methods D 143, these effectsare self correcting so that the measured strength is close to thetrue shear strengt
17、h of the wood. By analogy the same may betrue in this test method, however, other factors are alsoinvolved and may alter the relationship.4.1.3 The rate of loading affects the strength of an adhesivebond according to the adhesives rheological properties. Themore viscoelastic or plastic the adhesive,
18、 the greater effect.Thermosetting adhesives like urea- and phenol-formaldehydeare elastic. Their bond strengths can be measured over a rangeof loading rate from 0.038 to 1.27 cm/min 0.015 to 0.5in./min with no apparent affect. Thermoplastic adhesives likepolyvinyl acetate, hot melts, and elastomer-b
19、ased adhesivesexhibit a broad range of elastic, viscoelastic, and plasticbehaviors. Their bond strengths will be affected to varyingdegrees by changing the loading rate. Generally, increasing therate, increases the measured strength.4.2 This test method is suitable for product research anddevelopmen
20、t, qualifying adhesives in accordance with certainproduct or performance specifications, and monitoring bondingprocess control. This test method may be suitable for compar-ing and selecting adhesives, however, such comparisons mustbe made with caution since the measured strength of someadhesives may
21、 be different in different types of joints. Strengthvalues obtained by this test method are not suitable as designshear strengths values without adjustment by certain engineer-ing design factors.5. Apparatus5.1 The testing machine shall have a capacity of not lessthan 6810 kg 15 000 lb in compressio
22、n and shall be fittedwith a shearing tool containing a self-aligning seat to ensureuniform lateral distribution of the load. The machine shall becapable of maintaining a uniform rate of loading such that theload may be applied with a continuous motion of the movablehead to maximum load at a rate of
23、5 mm 0.20 in./min with apermissible variation of 625 %. The shearing tool shown inFig. 1 has been found satisfactory. The testing machine shall belocated in an atmosphere such that the moisture content of thespecimens developed under the conditions prescribed in Sec-tion 8 is not noticeably altered
24、during testing.6. Test Specimens6.1 Test specimens shall conform to the form and dimen-sions shown in Fig. 2. The specimens shall be cut from testjoints prepared as described in Sections 7 and 8.6.2 At least 20 specimens shall be tested, representing atleast four different joints.7. Preparation of T
25、est Joints7.1 Hard maple blocks (Acer saccharum or Acer nigrum),having a minimum specific gravity of 0.65 based on oven-dryweight and volume shall be selected (see Note 1). These blocksshall be of straight grain and free from defects including knots,birdseye, short grain, decay, and any unusual disc
26、olorationswithin the shearing area. The blocks shall be of suitable sizepreferably so that five test specimens may be cut from one testjoint as shown in Fig. 3. Blocks approximately 19 by 63.5 by304 mm 34 by 212 by 12 in. have been found to besatisfactory for this purpose. The grain direction shall
27、beFIG. 1 Shearing ToolD905082parallel to the longest dimension of the block. The blocks shallbe at the equilibrium moisture content recommended by themanufacturer of the adhesive. In the absence of such recom-mendation, the moisture content shall be from 10 to 12 %based on oven-dry weight as determi
28、ned on representativesamples in accordance with the “Moisture Determination”section of Test Methods D 143. The blocks shall be surfaced,just prior to bonding, preferably with a hand-feed jointer, andthe blocks weighed and assembled in pairs so that blocks ofapproximately the same specific gravity ar
29、e bonded together.The surfaces shall remain unsanded and shall be free from dirt.NOTE 1A method for selecting maple blocks of satisfactory specificgravity is described in the Appendix to this method. For referee tests, thespecific gravity of blocks may be determined in accordance with theprocedure d
30、escribed in the “Specific Gravity and Shrinkage in Volume”section of Test Methods D 143.7.2 The adhesive shall be prepared and applied to the blocksin accordance with the procedure recommended by the manu-facturer of the adhesive. The adhesive-coated blocks shall thenbe assembled and pressed, likewi
31、se in accordance with therecommendations of the manufacturer of the adhesive.8. Conditioning of Test Joints8.1 The joints, upon removal from pressure shall be condi-tioned at a relative humidity of 50 6 2 % and at a temperatureof 23 6 1C 73.4 6 2F either for a period of 7 days or untilspecimens reac
32、h equilibrium as indicated by no progressivechanges in weight, whichever is the shorter period. The lengthof this period of conditioning may be extended beyond thislimit by written agreement between the purchaser and themanufacturer of the adhesive.9. Preparation of Specimens9.1 Cut the specimens as
33、 shown in Fig. 3 so that the graindirection is parallel to the direction of loading during test. Takecare in preparing the test specimens to make the loadedsurfaces smooth and parallel to each other and perpendicular tothe height. Take care also in reducing the lengths of thelaminations to 44.4 mm 1
34、34 in. to ensure that the saw cutsextend to, but not beyond, the bond line. Measure the widthand length of the specimen at the bond line to the nearest 0.25mm 0.010 in. to determine the shear area.9.2 Retain specimens in the conditioning atmosphere de-scribed in Section 8 until tested, except during
35、 the cuttingoperations.10. Procedure10.1 Place the test specimen in the shearing tool so that theload may be applied as described in Section 5. The position ofthe specimen in one type of shearing tool is shown in Fig. 1.Apply the loading with a continuous motion of the movablehead at a rate of 5 mm
36、0.20 in./min to failure as prescribed inSection 5.11. Calculation11.1 Calculate the shear stress at failure in kilopascals(pounds-force per square inch) based on the bond line areabetween the two laminations measured to the nearest 0.06cm20.01 in.2, and report for each specimen together with theesti
37、mated percentage of wood failure. Practice D 5266 hasbeen found useful in estimating the percentage of wood failurein adhesive bonded joints.12. Report12.1 The report shall include the following:12.1.1 Complete identification of the adhesive tested, in-cluding type, source, manufacturers code number
38、s, form, etc.12.1.2 Application and bonding conditions used in prepar-ing the specimens.12.1.3 Conditioning procedure used for the specimens.12.1.4 Temperature and relative humidity in the test room.12.1.5 Number of specimens tested.12.1.6 Number of joints represented.12.1.7 Maximum and minimum shea
39、r stresses at failure andpercentages of wood failure. The standard deviation or allindividual test values, or both, for the failing load values andwood failure values may be included in the report at the optionof either the purchaser or the manufacturer of the adhesive.12.1.8 The average shear stres
40、s at failure and the averagepercentage of wood failure.13. Precision and Bias13.1 Precision:13.1.1 Precision has two components: repeatability at agiven test site and reproducibility between test sites. Theprecision of this test method is affected by many factorsMetric Equivalentsin.mm146.3341913444
41、.4250.8FIG. 2 Form and Dimensions of Test SpecimenMetric Equivalentsin.mm146.3341913444.4250.8FIG. 3 Test Joint Showing Method of Cutting Five TestSpecimensD905083including, but not limited to: (1) the wood species, (2) theboards selected, (3) grain direction, (4) growth ring orientation,(5) the qua
42、lity of the bonded joint, (6) the condition of theshear tool, (7) the precision on the testing machine, and (8) theoperator. When the specimen fails primarily in the wood, thenormally variability of the wood strength affects the precision.The coefficient of variation of shear strength parallel to th
43、egrain is 14 % for a given species of wood.13.1.2 Repeatability at a Given Site:13.1.2.1 In a study in which all the above factors wereclosely controlled and the specimens were bonded with phenol-resorcinol formaldehyde adhesive, the coefficient of variationranged from 2.4 up to 13.0 %, with most va
44、lues in the range of3to6%.13.1.2.2 In a study in which all the above factors, exceptboard and growth ring orientation, were controlled, the coef-ficients of variation ranged from 8 to 11 % for casein bondedspecimens, 4 to 12 % for two polyvinyl acetates, 22 to 27 % foran elastomer-based, and 14 to 2
45、1 % for phenol-resorcinolformaldehyde adhesive bonded specimens.13.1.3 Reproducibility from site to site:13.1.3.1 The reproducibility of this test method has not beenestablished.13.2 BiasBias is the difference between the true shearstrength of the adhesive bond and the strength measured by amethod t
46、hat is repeatable. Bias arises from the design, method,rate of loading the specimen, and from the strength of thewood.14. Keywords14.1 adhesive; bond; compression; compression loading;shear; strength propertiesAPPENDIX(Nonmandatory Information)X1. METHOD FOR SELECTING MAPLE BLOCKS OF SATISFACTORY SP
47、ECIFIC GRAVITYX1.1 Cut the hard maple blocks into some standard sizesuch as 19 by 63.5 by 304 mm 34 by 212 by 12 in. afterconditioning. Measure the linear dimensions of the blocks ininches, using a suitable caliper or other measuring device.Determine the percentage moisture content of the blocks ina
48、ccordance with the “Moisture Determination” section of TestMethods D 143. Do not use these samples in further tests.X1.2 Calculate the volume of the blocks to the nearest 1cm30.1 in.3 and express the average percentage moisturecontent to the nearest whole number. Determine the numericalvalue of the
49、factor for this moisture content by reference toTable X1.1, which is based on hard maple blocks that have aspecific gravity of 0.65 on the oven-dry weight and volumebasis and which were conditioned to various moisture contentvalues.X1.3 Multiply the factor in Table X1.1 by the volume of theblock in cubic inches to obtain the weight of the block in gramswhich would have a specific gravity of 0.65 on the oven-dryweight and volume basis.TABLE X1.1 Factors for Corrected Weight in GramsMoisture Content,%FactorA4 10.835 10.886 10.927 10.968 11.009 1
