MaTestLab > Test Standards > ASTM E647 Method for Measurement of Fatigue Crack Growth Rates

ASTM E647 Method for Measurement of Fatigue Crack Growth Rates

The ASTM E647 test method specifies standards for measuring crack growth rates, allowing for precise calculation of parameters such as the Paris law constants (C and m) or the da/dN against K relationship. The growth of fatigue cracks can result in catastrophic failure. This test method determines fatigue crack growth rates from near-threshold to Kmax controlled instability. Crack growth equations are used to predict the crack size starting from a given initial flaw and a crack growth equation can be used to ensure safety, both during designing and operation phases, by predicting the size of cracks.

Introduction to ASTM E647

ASTM E647 evaluates how fatigue crack growth impacts the lifespan of cyclically loaded components when data is obtained under normal conditions and supplemented with relevant fracture toughness, defect characterization, and stress analysis information. ASTM E647 testing helps engineers and researchers develop robust materials, optimize component designs, and establish maintenance schedules to prevent fatigue crack propagation.

ASTM E647 Test Method

ASTM E647 serves as a fundamental reference for measuring fatigue crack growth rates in metallic materials as follows:

Test Execution

The specimen is mounted securely in the testing apparatus, cyclic loading is applied, parameters are monitored and maintained parameters, The process is continued until the desired crack length or number of cycles are reached, and finally the cycle elapsed is recorded.

Data Analysis

Recorded crack length measurements and corresponding number of cycles are collected to create a crack growth curve. The crack growth rate (da/dN) is calculated using the measured crack length data and the elapsed number of cycles between measurements. The crack growth rate data is analyzed using statistical methods or regression techniques. The material’s resistance to fatigue crack growth is evaluated.

ASTM E647 Test Specimen

Specimen details	The specimen used in fatigue crack growth rate testing according to ASTM E647 is typically made of a metallic material relevant to the study or application. It is chosen based on the material’s behavior, crack growth characteristics, and compatibility with the testing equipment.
Specimen dimensions	The ASTM E647 standard defines the dimensions of specimens to ensure consistency and comparability. CT specimens have length, width, thickness, and crack size, while CCT specimens have length, width, thickness, and crack size and shape.
Specimen preparation	Specimen preparation involves machining the metallic material to obtain desired dimensions and geometry, maintaining integrity, and using surface finishing techniques to remove defects.

ASTM E647 Test Results

The crack growth curve provides a visual representation of how the crack grows under cyclic loading conditions. The crack growth rate (da/dN) is determined by calculating the slope of the curve. The Paris law constants (C and m) can be determined from the slope and intercept of the log(da/dN) versus log(K) relationship.

Other Tests related to ASTM E647

ASTM E647 is related to other standards such as ASTM E399 for linear-elastic plane-strain fracture toughness KIc of metallic materials and ASTM E561 standard test method for K-R curve determination.

FAQ's

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Please contact us for a detailed quote for your astm e647 testing needs. Cost incurred to carry out different astm e647 testing methodology depends on the type of raw material; number of samples, coupons, or specimens; test conditions, turn around time etc. Costs of some ASTM testing methods start from $100 and the final value depends upon the factors listed above. Please contact us for the best and latest prices.

How many samples are required for astm e647?

The required number of samples or specimens should comply with the procedure given in the astm e647 standard. However, the MaTestLab operations team can assist you for your special requirements once you share your testing details with us.

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The turnaround time for astm e647 test methodology depends upon the test procedure mentioned in the standard test document. However, we at MaTestLab understand your research requirements and hence try to get your test completed within the least possible time.

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