Chapter 8 281 In short, repeated grooming experiments are a version of a fatigue test, in that every fiber encounters an external stimulus during each comb or brush stroke. However, here we encounter the reverse scenario of that outlined in the single fiber fatigue work. That is, in the previous work, it was possible to control the magnitude of the applied stress, but it was unknown where real-life conditions occur. Now, it is presumed that real-life conditions are replicated relatively well, but we don’t know the magnitude of the stresses and strains. Nevertheless, recognizing the similarities between the two experiments introduces the idea that data from repeated grooming experiments can also be treated and modeled using fatigue testing principles. Experimental: In theory, repeated grooming experiments can be performed by hand, but it is less strenuous and more reproducible to perform the task automatically. Figure 21 shows the homemade device used at TRI. Figure 21. TRI’s custom-built repeated combing/brushing apparatus