Numerical Simulation of Crack Propagation
Numerical Simulation of Crack Propagation in Flexible Asphalt Attachments due to Traffic Loads
Under functional construction contracts, contractors are required to maintain the functions of a road over the agreed contract period. The resulting shift of risk from the client to the contractor requires a procedure that allows damage prediction and estimation of the useful life of a road pavement and reduces the contractor's construction and maintenance costs. In this context, analytical methods that allow computer simulation of pavement behavior and optimization of structure and materials can make an important contribution to more economical and safe pavement design. In Germany, the computational analysis and design of flexible road pavements is currently carried out in accordance with the RDO Asphalt 09. In the RDO Asphalt 09, particular attention is paid to a realistic description of fatigue phenomena on the underside of the asphalt layers as a result of tensile stresses. If the resulting external stress exceeds the fatigue resistance of the asphalt, fatigue cracking will occur (cracking from above and below). Crack initiation and propagation depend on temperature, stress and the ability of stress redistribution within the layers. The objective of this research project is to develop fundamentals for simulating the cracking behavior of flexible pavements. With these fundamentals, a better insight into the complicated relationships between microcrack formation, macrocrack initiation and crack propagation will be presented. Experimentally based findings on the crack behavior of asphalt and on crack propagation in common fatigue tests will be used. Furthermore, basic principles for an improved transfer of the results obtained in these fatigue tests to the crack behavior in real road pavements will be developed. With these fundamentals, important correlations for the prognosis of service life and remaining service life of flexible road pavements can be established, which are to be incorporated into the substance evaluation of asphalt pavements in the future.