1、UDC 669.1/.8: 620.11533 : 620.178.322.3 DEUTSCHE NORM March 198 nh I I c s .2 iir, 20 - LSr bl E f g c QO OOJ: w mm O?C : 5s *z Ed : $ o ; L! Os 5 !“ s: = O- Io, 0 52 ao a- 0- DIN Testing of metallic materials Flat bending fatigue test 50 142 Prfung metallischer Werkstoffe; Flachbiegeschwingversuch
2、Supersedes March 1941 edition As it is current practice in standards published by the International Organization for Standardization (ISO), the comma has been used throughout as a decimal marker. 1 Field of application This standard applies to flat specimens made of metallic materials and subjected
3、to alternating bending stress. 2 Purpose The flat bending fatigue test is intended for deter- mining the bending fatigue properties of flat specimens. Since the most highly stressed regions of the material lie in the surface zone of the specimens, with this test, the surface condition of the specime
4、ns is of particular importance. ao r5* EH s *ILI 3 Concepts Concepts, symbols and general information on the test procedure and evaluation of the results according to DIN 50 100. 1 4 Summary of method In the flat bending fatigue test, flat specimens are sub- jected to alternating bending stress by p
5、eriodic applica- tion of a bending moment or a torsion at the gripping ends or by periodic application of transverse loads. 5 Designation of method Designation of the flat bending fatigue test for metallic materials (A): Test DIN 50 142 -A 6 Apparatus Alternating bending machines or cyclic torsion o
6、r com- pression-tension fatigue testing machines with suitable special devices, complying with the requirements of DIN 51 228 and the general code of practice in DIN 51 220. 7 Specimens The specimens must be taken as flat specimens with rectangular test cross section. Details of the specimen shape a
7、nd dimensions are not specified. They will depend on the purpose of the test and the available testing machine. The dimensions required for determining the test cross section must be measured to the nearest t 0,Ol mm. The edges of the specimens must be smoothly machined in the region of the measurin
8、g length before testing so as to avoid cracks starting at the edges. This can be done for example by careful chamfering of the edges with a grindstone. Attention is drawn to the fact that with specimens of different shape the regions under high stress will be of different size. For this reason, the
9、results obtained will be dependent on the shape and dimensions of the speci- men. The condition of the material and the surface condition of the specimens (surface parameters, for example R, or R, and machining method) should be the same as required for the particular application. Attention is expre
10、ssly drawn to the fact that the method and direc- tion of machining of the specimen have a decisive influence on the test results. Moreover, care must be taken to ensure that the surface is not damaged either before or during the tests, for example by mechanical effects or unwanted corrosive effects
11、. 8 Procedure The specimen must be fitted in the grips without deforming it. Particular attention must be paid to the instructions supplied by the manufacturer of the testing machine when this is done. The specified stress on the specimen must be achieved as quickly as possible. It must not be excee
12、ded. In the case of test machines operating with a constant deflection of the specimen, perceptible changes can occur in the effective stress in the edge region of the specimen at the start of the test (number of load cycles N lo4) the deflection will have largely stabilized and this fact must be ch
13、ecked by making a number of measurements. If the testing machine must be stopped for this purpose, the down times necessary for the measurement must be kept as short as possible. The calculation of the test result shall be based on the value of the stress after it has stabilized. The calculation sha
14、ll take into account all the load cycles to which the specimen is subjected. Continued on pages 2 and 3 02.83 Sales No. 0106 COPYRIGHT DIN DEUTSCHES Institut Fur Normung E.V.- EnglishLicensed by Information Handling ServicesPage 2 DIN 50 142 If the deflections are read with dial gauges, the zero of
15、the dial gauges must be set before the start of stress (if necessary with optical or electrical auxiliary devices). Care must be taken to ensure that the test conditions, for example temperature of specimens, mean stress or mean strain, do not change during the test. Measure the atmospheric humidity
16、 in the testing room and note it in the test report. The inertia force error of the testing machine must be corrected. 9 Evaluation The stress occurring in the edge region of the specimen shall be calculated from the following formula: M bending moment W section modulus fJ= -= (the edge region stres
17、s calculated on the basis of a theo- retical elastic strain). The effective stress must be deter- mined separately for each specimen. The test results must preferably be plotted in a graph. The stress applied during the test shall be plotted on the Y-axis of the coordinate system, using either a lin
18、ear or logarithmic scale, and the number of cycles to failure on a logarithmic scale on the X-axis. Because of thedispersion normally occuring in the values obtained for the number of cycles to failure with tests carried out in the same way it is recommended that the design and evaluation of the tes
19、ts be based on statis- ticai principies). The results obtained with specimens that reach the prescribed limit for number of load cycles without failing must be specifically marked, for example by an arrow pointing towards the right. 10 Testreport The test report must refer to this standard and conta
20、in the following information: a) details of the specimen: - material (type, conditioning, dimensions, chemical analysis, characteristics determined in tension test) - manufacture (the region from which specimen was taken and direction, shape and dimensions of specimens, method of manufacture, type o
21、f heat treatment, storage time after heat treatment, stress concentra- tion factor, surface parameters*) b) details of the test procedure: - method of stress (e.g. three-point bending) - characteristics of stress (mean bending moment, bending stress, amplitude of moment, stress amplitude) (type, des
22、ignation) with information on the type of stress (for example by an eccentric) type of measurement (for example measurement of deflection, electrical measurement) method of gripping test frequency parameters describing the setting of the testing machine - testing machine c) information on the ambien
23、t conditions: - ambient temperature - atmospheric humidity - specimen temperature during the test, and where - where applicable, any special ambient conditions - fracture or unfractured specimen - position of fracture (in the test region, in the - number of cycles N to failure or to the end of the a
24、pplicable cooling medium d) information on the test result: region of the grips) test e) general information: - serial number of test - specimen number - date - testing centre, tester 1 It is intended to include these in a revised edition of 2, e.g. in accordance with DIN 4768 Part 1 DIN 50 100 COPY
25、RIGHT DIN DEUTSCHES Institut Fur Normung E.V.- EnglishLicensed by Information Handling ServicesDIN 50 142 Page 3 Standards referred to DIN 4768 Part 1 DIN 50 100 DIN 51 220 DIN 51 228 Determination of surface roughness R, R, R, with electric stylus instruments; basic data Testing of materials; conti
26、nuous vibration test; concepts, symbols, procedure, evaluation Material testing machines; general directions Material testing machines; fatigue testing machines; concepts, general requirements Previous edition DIN 50 142: 03.41 Amendments Compared with the March 1941 edition, the following amendment
27、s have been made: a) The application of the standard is no longer limited to light metals. b) With a view to a practical applicability of the test results it is recommended that the specimens used for the test be made of material in the same condition and having the same surface condition as those r
28、equired for the particular application. c) To ensure higher accuracy of the test results it is now required that the dimensions of the test cross section of each specimen tested must be determined. d) A recommendation is included that the tests be designed and evaluated statistically. e) The “Test r
29、eport“ clause has been included, which summarizes all the details that must be included in the report on a test complying with the requirements of this standard. Explanations This standard has been prepared by Working Group NMP 145 “Alternating stress test methods for metals“ of Normen- ausschuss Materialprfung (NMP) (Materials Testing Standards Committee). International Patent Classification G O1 N 3/00 COPYRIGHT DIN DEUTSCHES Institut Fur Normung E.V.- EnglishLicensed by Information Handling Services
