Experimental evaluation of monotonic and cyclic fracture behavior using disk-shaped compact tension test and released energy approach

Na Chiangmai, Chaiwat

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https://hdl.handle.net/2142/73043 Copy

Description

Title

Experimental evaluation of monotonic and cyclic fracture behavior using disk-shaped compact tension test and released energy approach

Author(s)

Na Chiangmai, Chaiwat

Issue Date

2015-01-21

Director of Research (if dissertation) or Advisor (if thesis)

Buttlar, William G.

Doctoral Committee Chair(s)

Buttlar, William G.

Committee Member(s)

• Al-Qadi, Imad L.
• Thompson, Marshall R.
• Dave, Eshan V.

Department of Study

Civil & Environmental Eng

Discipline

Civil Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Monotonic Fracture
• Cyclic Fracture
• Released Energy
• disk-shaped compact tension (DC(T)) Test
• Fatigue Test

Abstract

This thesis involves the evaluation of fracture behavior of asphalt concrete under monotonic and cyclic loading using the disk-shaped compact tension (DC(T)) test and a released-energy based approach. The standard DC(T) test was revised to facilitate both monotonic and cyclic loading tests, including some modifications of the test geometry and testing modes. The research was motivated to explore possible extensions of the DC(T) test device to consider cyclic fracture phenomena such as cyclic thermal cracking, block cracking and reflective cracking. Five different asphalt concrete mixtures were tested for both loading mechanisms across four test temperatures (-12, 0, 10, and 20oC). After an extensive exploratory stage, the load-controlled testing mode utilizing a sine waveform and a frequency of 0.5 Hz with no rest period were selected as the main testing parameters for this study. In addition, peak load obtained from the monotonic DC(T) test was used as a reference value for determining loading magnitudes of the cyclic DC(T) test for a given mixture and test temperature. For data analysis, the released energy approach was introduced as a key concept to characterize the cyclic fracture data generated in this study. Stemming from this approach, a released energy rate parameter, R2, was identified with the characteristic of mixture and temperature independence. By correlating a fracture energy parameter (Gf) to released energy rate (R2), cyclic loading behavior could be predicted based upon three different data sets deriving from the DC(T) test: one involving a comprehensive cyclic loading testing suite; a slightly simpler method involving a limited number of required cyclic tests, and; a highly simplified approach where cyclic fracture behavior was predicted form monotonic fracture test results alone (standard DC(T) fracture energy). All three prediction methods were shown to be plausible, but as expected, the more rigorous the testing suite, the more accurate the prediction. Furthermore, monotonic and cyclic fracture behaviors were monitored using a webcam-based imaging technique to investigate fracture processes at a macro-scale level. As a result, each stage of cracking, including crack initiation and crack propagation, could be potentially predicted based on the cyclic test data through a relation of the crack initiation to number of cycles to a failure and crack propagation ratios, respectively.

Graduation Semester

2014-12

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http://hdl.handle.net/2142/73043

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Copyright 2014 Chaiwat Na chiangmai

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