You are on page 1of 5 Search inside document Designation: E 96 Reapproved e1 Standard Practice for Conducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials1 This standard is issued under the fixed designation E ; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon e indicates an editorial change since the last revision or reapproval. Terminology strength of metallic materials in the fatigue regime where the strains are predominately elastic, both upon initial loading and 3.
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A number in parentheses indicates the year of last reapproval. This practice is limited to the fatiguetesting of axial unnotched and notched specimens subjected toa constant amplitude, periodic forcing function in air at roomtemperature. This practice is not intended for application inaxial fatigue tests of components or parts. Referenced Documents2. Significance and Use4. The results may also be used as a guide for theselection of metallic materials for service under conditions ofrepeated direct stress.
To do so would require the control or balance of what areoften deemed nuisance variables; for example, hardness,cleanliness, grain size, composition, directionality, surfaceresidual stress, surface finish, and so forth.
Thus, whenembarking on a program of this nature it is essential to defineand maintain consistency a priori, as many variables asreasonably possible, with as much economy as prudent.
Allmaterial variables, testing information, and procedures usedshould be reported so that correlation and reproducibility ofresults may be attempted in a fashion that is consideredreasonably good current test practice.
Specimen Design5. Current edition approved May 1, Published June Originallyapproved in Last previous edition approved in as E — United States1capacity, and the form in which the material is available. However, the design should meet certain general criteriaoutlined below The acceptable ratio of the areas test section to gripsection to ensure a test section failure is dependent on thespecimen gripping method. Threaded end specimens mayprove difficult to align and failure often initiates at these stressconcentrations when testing in the life regime of interest in thispractice.
A caveat is given regarding the gage section withsharp edges that is, square or rectangular cross section sincethese are inherent weaknesses because the slip of the grains atsharp edges is not confined by neighboring grains on two sides.
Because of this, a circular cross section may be preferred ifmaterial form lends itself to this configuration. The size of thegripped end relative to the gage section, and the blend radiusfrom gage section into the grip section, may cause prematurefailure particularly if fretting occurs in the grip section or if theradius is too small.
Readers are referred to Ref 1 should thisoccur. Surfaces intended tobe parallel and straight should be in a manner consistent with8. NOTE 2—Measurements of dimensions presume smooth surface fin-ishes for the specimens.
In the case of surfaces that are not smooth, dueto the fact that some surface treatment or condition is being studied, thedimensions should be measured as above and the average, maximum, andminimum values reported. To ensure test section failure, the gripcross-sectional area should be at least 1.
The blending fillet radius should be at least eighttimes the test section diameter to minimize the theoreticalstress concentration factor, Ktof the specimen. The test sectionlength should be approximately two to three times the testsection diameter. For tests run in compression, the length of thetest section should be approximately two times the test sectiondiameter to minimize buckling. The reduced section length should be greater than three timesthe minimum test section diameter.
Otherwise, the samedimensional relationships should apply, as in the case of thespecimens described in 5. In view of this, no maximum ratio of area grip totest section should apply. The value of 1. Otherwise, the sections maybe either of two types The ratio ofspecimen test section width to thickness should be between twoand six, and the reduced area should preferably be between0. The test section length should be approximately two to threetimes the test section width of the specimen.
For specimensthat are less than 0. Also, Refs , although they pertain tostrain-controlled testing, may prove of interest since they dealwith sheet specimens approximately 0. Thearea restrictions should be the same as for the specimendescribed in 5. Also, specific notched geometry, notch tip radius,information on the associated Ktfor the notch, and the methodand source of its determination should be reported. Specimen Preparation6. Impropermethods of preparation can greatly bias the test results.
In viewof this fact, the method of preparation should be agreed uponprior to the beginning of the test program by both the originatorand the user of the fatigue data to be generated.
Since specimenpreparation can strongly influence the resulting fatigue data,the application or end use of that data, or both, should beconsidered when selecting the method of preparation. Appen-dix X1 presents an example of a machining procedure that hasbeen employed on some metals in an attempt to minimize thevariability of machining and heat treatment upon fatigue life.
Regardless of themachining, grinding, or polishing method used, the final metalremoval should be in a direction approximately parallel to thelong axis of the specimen. This entire procedure should beclearly explained in the reporting since it is known to influencefatigue behavior in the long life regime.
One exception may be where these parameters are understudy. Fillet undercutting can be readily determined by inspec-tion. Assurance that surface residual stresses are minimized canbe achieved by careful control of the machining procedures. Itis advisable to determine these surface residual stresses withX-ray diffraction peak shift or similar techniques, and that thevalue of the surface residual stress be reported along with thedirection of determination that is, longitudinal, transverse,radial, and so forth.
The storage medium should generallybe removed before testing using appropriate solvents, ifnecessary, without adverse effects upon the life of the speci-mens. Obvious abnormalities, such as cracks,machining marks, gouges, undercuts, and so forth, are notacceptable. Specimens should be cleaned prior to testing withsolvent s non-injurious and non-detrimental to the mechanicalproperties of the material in order to remove any surface oilfilms, fingerprints, and so forth.
Dimensional analysis andFIG. Equipment Characteristics7. The test forces should be monitored continuously in the earlystage of the test and periodically, thereafter, to ensure that thedesired force cycle is maintained. Itis beyond the scope of Practice E to extrapolate beyond thisrange or to extend this assumption to other materials systemsthat may be viscoelastic or viscoplastic at ambient test tem-peratures and within the frequency regime mentioned.
ASTM E466 Uji Fatik Logam
Obvious abnormalities, such as cracks, machining marks, gouges, undercuts, and so forth, are not acceptable. The trial test specimen should be turned about its axis, installed, and checked for each of four orientations within the? Paper Standards and Packaging Standards. E e1 E E E As a conservative general measure, this procedure is recommended unless: E — 07 fatigue test the permanent deformation of the unbroken but tested specimens for example, ast, change in cross-section area of test section should be reported. It is important that the accuracy of alignment be kept consistent from specimen to specimen. The trial specimen should be rotated about its longitudinal axis, installed and checked in both orientations within the?
ASTM E466 Load Controlled Constant Amplitude Fatigue Tests of Metals
ASTM E is limited to the fatigue testing of axial unnotched and notched specimens subjected to a constant amplitude, periodic forcing function in air at room temperature. Testing Procedure Place the specimen securely in the grips of the testing machine. Specimens can be round or flat. Take care to adjust the specimen symmetrically to distribute the load uniformly over the cross section.