What Does Fatigue Cracking Mean?
Fatigue cracking occurs when the progressive weakening of a structure leads to the splitting or separating of its material into parts. In trenchless construction, underground infrastructure such as pipelines, tunnels, or borehole walls may be susceptible to fatigue cracking. Detection of these defects can prevent disaster by allowing for timely repair and maintenance.
Trenchlesspedia Explains Fatigue Cracking
Time takes its toll on all things, including materials used in underground pipes and tunnels. Fatigue cracking is a phenomenon that results from the essential properties of fracture mechanics. When stress factors on a structure exceed its tensile strength, a process that may progress over time, defects such as crack displacement may occur. The word fatigue is used because the material seems to become 'tired' of the cyclical and repeated stress.
Cracks in a cylindrical body, such as a pipe, may be along it or around it. A crack moving along a pipe is called an axial crack. A circumferential crack moves around the circle of a pipe.
Time-lapse photography has been used to show the progress of fatigue cracks. Researchers study such events to track and record the properties of various materials when under stress. Mechanical properties are quantified so that inspectors may assess defects and the durability of the material.
Regular inspection of pipes and tunnels may reveal fatigue cracks. Trenchless rehabilitation techniques are often used to repair fatigue cracks once identified.