Mechanical joining Tensile shear testing of single joint specimens Specimen dimensions and test procedure

Transcription

1 Mechanical joining Tensile shear testing of single joint specimens Specimen dimensions and test procedure Assemblage mécanique Essais quasi statiques de traction-cisaillement des échantillons à jonction unique (de: Mechanisches Fügen Scherzugprüfung von Einpunktproben Probenmaße und Prüfung) Parts of the draft shaded in yellow need further consideration. Dokument-Typ: Norm Dokument-Untertyp: Dokumentstufe: Entwurf Dokumentsprache: D

2 Contents Page Foreword Foreword Scope Normative references Terms and definitions Test specimens and types of tests Test equipment and test procedure Failure mode Test report...9 A.1 General...10 A.2 Typical failure modes of semi-tubular self piercing rivet joints under shear load...10 A.3 Typical failure modes of solid self piercing rivet joints...11 A.4 Typical failure modes of clinch joints...12 A.5 Typical failure modes of screwed joints...13 A.6 Typical failure modes of joints made with self clinching or self piercing nuts...14 A.7 Typical failure modes of joints made with self clinching or self piercing bolts...15 A.8 Typical failure modes of blind rivet joints...16 A.9 Typical failure modes of lock bolt joints...17 A.10 Slippage in a mechanical joint

3 1 Scope This standard specifies the geometry of the test specimens and the procedure for the tensile shear testing of single mechanical joints on single and multi-layer specimens up to a single sheet thickness of 4,5 mm. The term sheet, as used in this standard, includes extrusions and cast materials. The purpose of the tensile shear test is to determine the mechanical characteristics and failure types of the joints made with the different methods. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO , General tolerances Tolerances for linear and angular dimensions without individual tolerance indications ISO Metallic materials Verification of static uniaxial testing machines Part 1: Tension/compression testing machines Verification and calibration of the force-measuring system 3 Terms and definitions For the purpose of this document, the following terms and definitions apply. 3.1 tensile shear load F max. maximum load, recorded in the test Note If required, further characteristic data, e.g. F p0,2 (see 3.2), stiffness of the specimen c (see 3.6) or slope of the force curve γ, energy dissipation W (see 3.7), can be determined according to the shear diagram given in Figure elastic load limit F p0,2 maximum load before plastic or permanent deformation of 0,2 % occurs 3.3 displacement s increase in the length of the specimen during the tensile shear test 3.4 displacement at the maximum load F max s Fmax amount of displacement measured at maximum load F max 3.5 displacement at 0,3F max s 0,3Fmax amount of displacement measured at 0,3F max 4

4 3.6 stiffness in elastic range c ratio of increase of load to the increase of elongation in the elastic range (c = ΔF/Δs) 3.7 dissipated energy W work or area under the load curve 3.8 dissipated energy up to F max W Fmax area under the force curve up to the point of maximum tensile shear load F max W F max = s F max s= 0 F ds 3.9 dissipated energy up to 0,3F max W 0,3Fmax area under the load curve up to the point where the tensile shear force drops to 30% of F max W 0,3F max s0,3 F max = F ds s= dissipated energy up to fracture W fracture total area under the force curve W fracture = s fracture s= 0 F ds 3.11 displacement at maximum load F max s Fmax displacement at which the maximum load F max is recorded 3.12 displacement at 0,3F max s 0,3Fmax displacement at which 0,3F max is recorded 3.13 form fit (Dr. Singh) 3.14 force fit (Dr. Singh) 5

5 4 Test specimens and types of tests Tolerances according to ISO are applicable to the dimensions of the specimens given in Table 1. ((Missing reference to Figures 1 and 2)) Key a b l c l s l g l t t 1, t 2 overlap coupon width length of clamped area total length of specimen specimen length between clamps coupon length sheet thickness 1 shim plates Figure 1 Single-lap tensile shear test specimens ((2 nd specimen with indication of visual and blind side and reverse)) Key 1 shim plates Figure 2 Examples of different sheet testing arrangements for tensile shear test specimens 6

6 Stacking order of the sheets, the joining directions, the visible and blind side, etc. shall be agreed upon between the contracting parties. Table 1 Specimen dimensions Thickness of sheet t 1; t 2 Overlap a Specimen width b Length of clamped area l c Specimen length between clamps mm mm mm 4,5 5 d 7 d NOTE Total specimen length: l s = l g + 2 l c, where the length of the clamped area is to be selected in accordance with the testing machine being used. d Shank diameter of blind rivets and self-locking collar bolts as well as nominal diameter of thread at screws. l g 5 Test equipment and test procedure The test specimen is clamped in a tensile testing machine according to ISO , in such a manner, that the clamps are at the required distance from one another. For sheet thicknesses > 1 mm or where the ratio of the thicknesses is >1,4, shim plates shall be used for clamping the test specimen in the grips of the tensile testing machine to ensure load concentricity (see Figure 3 b) and c)). Shim plates can be joined by suitable joining method, e.g. resistance spot welding, adhesive bonding. Testing shall be carried out at room temperature. The speed of testing is 10 mm/min. NOTE If tests at higher speeds show that the higher testing speed has no influence on the test results, then the higher testing speed may be used for the tensile shear tests. The elongation shall be measured as the displacement of the crosshead or by using extension calliper gauges, laser measuring equipment or other suitable extension sensors with a defined length directly on the specimen. Measurements made using signals from the crosshead should, if necessary, be corrected by taking the stiffness of the machine into consideration. The sensing method used and the defined length of the specimen measured shall be recorded in the test report. Tests results are comparable only when the tests are carried out under identical boundary conditions. 7

7 Key a) Test arrangement without shim plates b) Test arrangement with shim plates (two layers) c) Test arrangement with shim plates (three layers) 1 shim plates Figure 3 Set-up for tensile shear test specimens Figure 4 illustrates a load elongation diagram for specimens with form and force fit joints. Corresponding diagrams for force fit joints can exhibit slippage before the yield point. In addition different diagrams can be the result of different combinations of joining methods, sheet materials and thicknesses, as well as specimen geometries. F F max F p 0,2 W 0,3F max γ s Fmax s 0,3 Fmax s Fracture s Key F s load elongation Figure 4 Characteristic values of a load-elongation diagram for the tensile shear test 8

8 6 Failure mode The failure mode after tensile shear testing shall be classified according to Annex A. 7 Test report The test report shall contain the following information: a) name of the operator and/or the examining body; b) designation of this standard (ISO 12996); c) date and signature of the operator or the examining body; d) joining technology; e) joining parameters and joining equipment, fastener used; f) specimen material and material condition; g) specimen dimensions; h) testing machine, test speed; i) defined length on specimen and gauge type used for displacement measurements single values, mean values and standard deviation of the characteristic values; j) individual test results, standard deviation, Coefficient of variation for the forces and the elongation k) failure mode; l) any additional remarks if required. 9

9 Annex A (normative) Types of joint failure A.1 General Depending on the joining technology, different types of failure can occur. Some of these are specific to the joining technology employed and should be recorded in the test report. Typical failure modes for clinch, self piercing rivet and screwed joints are shown, by way of example, in Figures A.1 to A.8. Criteria for a failure of a mechanical joint are to be agreed between contracting parties. Following figures give typical failure modes at the end of the test. A.2 Typical failure modes of semi-tubular self piercing rivet joints under shear load a) Rivet pull out from bottom sheet b) Pull out of rivet head c) Failure of the specimen material d) Rivet failure Figure A.1 Typical failure modes of semi-tubular self piercing rivet joints under shear load 10

10 A.3 Typical failure modes of solid self piercing rivet joints a) Rivet pull out from bottom sheet b) Pull out of rivet head c) Failure of the specimen material d) Rivet failure Figure A.2 Typical failure modes of solid self piercing rivet joints under shear load 11

11 A.4 Typical failure modes of clinch joints a) Pull out b) Neck fracture c) Neck fracture with plastic deformation (mixed mode failure) d) Pull out with neck fracture (mixed failure) Figure A.3 Typical failure modes of clinch joints 12

12 A.5 Typical failure modes of screwed joints a) Thread in specimen stripped b) Upper (head side) component fails Figure A.4 Typical failure modes of screwed joints (self drilling and thread forming screws) 13

13 A.6 Typical failure modes of joints made with self clinching or self piercing nuts a) Impermissible specimen deformation or pull out of the nut b) Specimen tear-out c) Bolt failure Figure A.5 Typical failure modes of joints made with self clinching or self piercing nuts 14

14 A.7 Typical failure modes of joints made with self clinching or self piercing bolts a) Impermissible specimen deformation or pull out of the bolt b) Specimen tear-out c) Bolt failure Figure A.6 Typical failure modes of joints made with self clinching or self piercing bolts 15

15 A.8 Typical failure modes of blind rivet joints a) Impermissible specimen deformation or rivet pull b) Specimen tear out c) Blind rivet failure Figure A.7 Typical failure modes of blind rivet joints 16

16 A.9 Typical failure modes of lock bolt joints a) Impermissible specimen deformation or pull out of the bolt b) Specimen tear out c) Lock bolt failure Figure A.8 Typical failure modes of lock bolt joints 17

17 A.10 Slippage in a mechanical joint Figure A.9 Typical failure mode of slippage in a mechanical joint 18