BS-A-305-1994 ISO-7961-1994.pdf

BRITISH STANDARD BS A 305:1994 ISO 7961:1994 Bolts Test methods Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:32:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS A 305:1994 This British Standard, having been prepared under the direction of the Aerospace Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 August 1994 © BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference ACE/12 Draft for comment 91/82709 DC ISBN 0 580 23219 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Aerospace Standards Policy Committee (ACE/-) to Technical Committee ACE/12, upon which the following bodies were represented: The Association of Electronics, Telecommunications and Business Equipment Industries British Industrial Fasteners Federation Ministry of Defence Society of British Aerospace Companies Ltd. Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:32:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS A 305:1994 © BSI 12-1999i Contents Page Committees responsibleInside front cover National forewordii 1Scope1 2Normative references1 3Tests1 4Test validity10 5Test reports10 Annex A (normative) Calibration of apparatus11 Annex B (normative) Test reports11 Annex C (informative) Formulae12 Figure 1 Tensile test Test device2 Figure 2 Tensile test Position of the nut in relation to the complete threads (shank side)2 Figure 3 Tensile test Upper and lower cup details3 Figure 4 Double shear test Test device4 Figure 5 Double shear test Upper and lower blocks5 Figure 6 Stress corrosion test Test cylinder (principle)10 Table 1 Rates of load application Tensile test4 Table 2 Rates of load application Double shear test6 Table B.1 Information to appear in test report11 List of referencesInside back cover Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:32:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS A 305:1994 ii © BSI 12-1999 National foreword This British Standard has been prepared under the direction of the Aerospace Standards Policy Committee. It is identical with ISO 7961:1994 Aerospace Bolts Test methods, published by the International Organization for Standardization (ISO). Cross-reference. The Technical Committee has reviewed the provisions of ISO 7500-1:1986, to which normative reference is made in the text, and has decided that they are acceptable for use in conjunction with this standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 12, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:32:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS A 305:1994 © BSI 12-19991 1 Scope This International Standard specifies test methods for bolts for aerospace constructions. It is applicable whenever quoted in reference. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 7500-1:1986, Metallic materials Verification of static uniaxial testing machines Part 1: Tensile testing machines. 3 Tests 3.1 Tensile test at ambient temperature 3.1.1 Apparatus 3.1.1.1 Test device (see Figure 1). The test device shall be centred such that the stress at four equi-spaced points around the test sample is uniform within 1 %, or such that the coaxiality between the bolt and the clearance holes is less than or equal to 0,025 mm to ensure the application of the tensile load along the axis of the bolt1). Other types of device may be used provided they respect the requirements of Figure 3. 3.1.1.1.1 Cups, fixed or removable, in conformity with Figure 3, which specifies only functional requirements. 3.1.1.1.2 Test nut (free-running or self-locking) or threaded part (assuming the role of a nut), of sufficient strength to guarantee bolt failure. 3.1.1.2 Tapered spacer, placed under the head during the test, when required by the procurement specification or definition document to evaluate the effect of angularity. The minimum clearance between the hole and the bolt shank shall be 0,13 mm. At least 90 % of the bolt bearing area shall be supported by the spacer which shall have a diameter sufficient to support the width across the corners of the bolt. The tolerance on the hole diameter in the spacer shall bemm. 3.1.1.3 Washers, used under bolt heads or nuts only in the case outlined in 3.1.1.2. 3.1.1.4 Tensile or compressive test machine, depending on the fixture, capable of applying the test loads. 3.1.2 Procedure 3.1.2.1 Assemble the bolt in the test device (3.1.1.1) as shown in Figure 1. Install the nut (3.1.1.1.2) as shown in Figure 2. Place the complete assembly between the loading platens of the machine. 3.1.2.2 Apply the load specified in the procurement specification or definition document at the rate specified in Table 11), in a controlled way. 3.2 Double shear test 3.2.1 Apparatus See Figure 4 and Figure 5, the latter only defining functional requirements. NOTE 1Totally enclosed top and bottom blades may be used as an alternative. 3.2.2 Procedure 3.2.2.1 Assemble the bolt into the lower part of the guillotine. The blend radius under the head and the threaded portion shall not be in contact with the lower part of the guillotine (see Figure 4). 3.2.2.2 Apply the load required in the procurement specification or definition document at the rate specified in Table 2, in a controlled way. If this load is attained without breakage of the bolt, the test may be terminated1). 1) Calibration requirements: see ISO 7500-1:1986 and Annex A of this International Standard. +0,08 0 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:32:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS A 305:1994 2 © BSI 12-1999 Figure 1 Tensile test Test device Figure 2 Tensile test Position of the nut in relation to the complete threads (shank side) Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:32:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS A 305:1994 © BSI 12-19993 Figure 3 Tensile test Upper and lower cup details Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:32:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS A 305:1994 4 © BSI 12-1999 Table 1 Rates of load application Tensile test Nominal shank diametera Rate kN/min Nominal shank diametera Rate kN/min Nominal shank diametera Rate kN/min 3 4 5 6 7 8 10 5 9 14 20 27 35 55 12 14 16 18 20 22 24 80 110 140 180 220 270 320 27 30 33 36 39 400 500 600 700 850 a For other shank diameters, bolts shall be tested at a loading rate, accurate to ± 10 %, of 750 N per minute per 1 mm2 of nominal shank cross-section. Figure 4 Double shear test Test device Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:32:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS A 305:1994 © BSI 12-19995 Figure 5 Double shear test Upper and lower blocks Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:32:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS A 305:1994 6 © BSI 12-1999 Table 2 Rates of load application Double shear test 3.3 Tension fatigue test 3.3.1 Apparatus 3.3.1.1 Test device (see Figure 1). Universal joints and spherical seats shall not be used in the test column. The test device shall be centred such that the stress at four equi-spaced points around the test sample shall be uniform within 3 % of the mean stress value2). Other types of device may be used provided they respect the requirements of Figure 3. Test bolts shall not be re-used. 3.3.1.1.1 Cups, fixed or removeable, in conformity with Figure 3, which specifies only functional requirements. 3.3.1.1.2 Test nut or threaded part (assuming the role of a nut), with a height greater than or equal to 0,8D and of sufficient strength to ensure bolt breakage. NOTE 2Test nuts or threaded parts may be re-used provided that it meets the dimensional requirements and has not been damaged by a previous test. For referee purposes, only unused nuts or threaded parts shall be used. 3.3.1.2 Load measuring system, of an accuracy within ± 2 % of the applied maximum load2). 3.3.1.3 Automatic load maintaining system 3.3.1.4 Fixtures, designed to incorporate the features indicated in Figure 3. 3.3.2 Procedure 3.3.2.1 Installation Test bolts shall be assembled so that a minimum of two and a maximum of three complete threads are exposed between the nut or threaded part (3.3.1.1.2) bearing face and incomplete threads on the shank side. In the case of flush head bolts, the bearing between the bolt head and the loading cup in which it is to be tested shall be uniform. There shall be no contact in the head-shank junction area. 3.3.2.2 Test conditions 3.3.2.2.1 Torque There shall be no tensile stress due to torque or any other installation procedure. 3.3.2.2.2 Load level The fatigue test loads shall comply with the values specified in the procurement specification or definition document. 3.3.2.2.3 Frequency The frequency of the test shall conform with the requirements of the procurement specification or definition document. The maximum temperature of the bolt during test shall not exceed 50 °C. 3.4 Stress durability test of ambient temperature 3.4.1 Apparatus 3.4.1.1 For torque or elongation loading 3.4.1.1.1 Steel blocks or spacers, heat treated to obtain a minimum Rockwell hardness of 45 HRC. 3.4.1.1.2 Threaded part, with sufficient strength to withstand the full tensile strength of the bolt being tested. 3.4.1.2 For external loading 3.4.1.2.1 Test device, as specified in 3.1.1.1. 3.4.1.2.2 Adapted fixture2) 3.4.2 Procedure Assemble the bolt in the test device (3.4.1.2.1) and apply the load specified in the procurement specification or definition document. Nominal shank diametera Rate kN/min Nominal shank diametera Rate kN/min Nominal shank diametera Rate kN/min 3 4 5 6 7 8 10 10 18 27 40 54 70 110 12 14 16 18 20 22 24 160 215 280 350 440 530 630 27 30 33 36 39 800 990 1 200 1 400 1 700 a For other shank diameters, bolts shall be tested at a loading rate, accurate to ± 10 %, of 750 N per minute per 1 mm2 of double the nominal shank cross-section. 2) Calibration requirements: see ISO 7500-1:1986 and Annex A of this International Standard. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:32:48 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS A 305:1994 © BSI 12-19997 For the torque loading method, the load is achieved by torque tightening to a pre-determined torque; this torque may be determined by formula or by calibrating torque against a load cell assimilating the test assembly3). For the elongation loading method, the load is achieved by measuring bolt extension; this extension may be determined by formula or by calibrating extension against a load cell assimilating the test assembly3). During the test, the loaded portion of the bolt shank shall have two full threads exposed between the incomplete threads on the shank side and the bearing face of the threaded part. Keep the bolt at ambient temperature in the loaded condition for the period of time specified in the procurement specification or definition document. At the end of this time, disassemble and examine the bolt for the presence of cracks. Bolts suspected of having cracks shall be sectioned and microscopically examined using × 100 magnification. Cracked or fractured test bolts constitute failure of the bolt. 3.5 Inspection for grinding burns 3.5.1 Procedure 3.5.1.1 Clean Remove all foreign matter from the bolts such as grease, dirt or oxide film. 3.5.1.2 Wetting test Rinse the bolts in cold water. If water breaks occur, reclean the bolts. 3.5.1.3 “Nital” etch Immerse the bolts for 2 min to 2,5 min in a 3 % (V/V) solution of nitric acid (relative density 1,38) in ethanol, at ambient temperature. Agitate the bath. 3.5.1.4 Rinse Rinse the bolts for at least 2 min in running water at a temperature below 25 °C. 3.5.1.5 Bleaching Immerse the bolts for 2 min to 2,5 min in a 5 % (V/V) solution of hydrochloric acid (relative density 1,18) in ethanol, at ambient temperature. Agitate the bath. 3.5.1.6 Rinse Rinse the bolts for 10 s to 30 s in running water at a temperature below 25 °C. 3.5.1.7 Neutralization Neutralization may be performed with either of the following baths: 3.5.1.7.1 Ammonia solution Immerse the bolts for 30 s to 60 s in a solution of 50 g/l of ammonia (relative density 0,90), at ambient temperature. 3.5.1.7.2 Soda solution Immerse the bolts for 30 s to 60 s in a solution of 50 g/l of soda at ambient temperature. 3.5.1.8 Rinse Rinse the bolts for 10 s to 30 s in running water at a temperature below 25 °C. 3.5.1.9 Dry Dry the bolts with filtered compressed air at ambient temperature. 3.5.1.10 Examine for grinding burns These burns appear as either white streaks (untempered martensite) or dark grey (zone of overtempering) on an even light grey background on the surface of the bolts. 3.5.1.11 De-embrittle Carry out a maximum of 12 h of “Nital” etch (3.5.1.3) de-embrittlement treatment on the bolts at a temperature of 130 °C ± 10 °C or 190 °C ± 10 °C for at least 2 h, depending on whether the tempering temperature of the parts is less than or equal to 200 °C or greater than 200 °C. NOTE 3After bleaching (3.5.1.5) and up to drying (3.5.1.9), operations should be carried out quickly to avoid oxidation. This oxidation builds up a chamois colour reducing contrast at a defect. Rinsing in running water at a temperature below 25 °C produces a uniform light grey colour on bolts without grinding defects, instead of a chamois colour for higher temperatures. 3.6 Tensile test at elevated temperature 3.6.1 Apparatus 3.6.1.1 Test device, as specified in 3.1.1.1. Materials and dimensional tolerances shall be consistent with the t