hello everyone,
i am working on simulating the cracking initiation and propagation using 2D XFEM by ABAQUS using monotonic and repeated loading.
I did two experimental test, fracture test for semi circular asphalt samples under three point load by using constant loading rate of 50/min, i got the load and displacement for test,
the second test, repeated load test by using low load cycle of 15% of fracture load, i got the load, displacement, and horizontal displacement for the SCB sample, the pic of samples and date are attached.
thank you for your time
Hello Due to the fact that the breaking of the samples is based on the properties of bitumen and the aggregates which are harder, cause test errors. So I guess there will be changes in the validity of this test in the future.
I got very good matching between the experimental work and FEM Work, but the problem is in the softening behaviour which is due to the deformation in the plastic zone,
Thus i am tring to define the creep behaviour of asphalt mixture. My question is how i can extract the time base or strain base power low parameters for the creep data?
As far as I know, this test is used to check the type of failure and crack spread. So it only works in the elastic state. We kept the samples in the freezer for one day so that they would not deform during the test.
Best.
This test has done at intermediate temperature of 25 C where plastic deformation is expected around the crack tip.
An attached file, I hope it is useful
the use of these fracture tests are limited to laboratory cast samples. Recent work on the disk-shaped compact tension (DCT) specimen geometry has shown it to give accurate and reliable load-CMOD curves and fracture energy values for asphalt concrete materials at low temperatures (Wagoner et al. 2005, 2006; Kim, H. and Buttlar 2009, Kim, M. and Buttlar 2009, Zofka and Braham 2009).
Based on recent studies, the SCB fracture test have very rialable results and has been standardized by different institutions...
AASHTO TP124 Semi-Circular
determine the fracture energy and post peak slope of asphalt mixtures using semi-circular specimens in the Flexibility Index Test (FIT) conducted at an intermediate test temperature.
ASTM D8044 Semi-Circular Bend accurately determine the cracking resistance at Long Term Pavement Performance (LTPP) database intermediate temperatures using semi-circular bend asphalt mix samples tested monotonically.
AASHTO TP105 ...... accurately determine the fracture energy of asphalt mixtures using the semi-circular bend geometry (SCB).
EN 12697-44 accurately determine crack propagation by semi-circular bending test.
Best regards
I think this paper maybe help you
- DOI: 10.1080/14680629.2012.657049
Hasanain Radhi Radeef
Hi Mr. Radeef,
You should use "Time hardening power law equation" to determine creep parameters of asphalt mixture (A, n, m). You can use Origin, Excel, Matlab etc. to perform Curve Fitting. In ABAQUS documentation, formulation is, Strain rate=A*(Stress^n)*(time^m). "m" must be "-1
Thank you for your answer, already i had used power law and fractional time-dependent viscoelatic element to convert the creep data into relaxation modulus data. After that i have evaluate the data using abaqus.
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