June 15, 2014
June 15, 2014
June 18, 2014
Division Experimentation & Lab-Oriented Studies
24.90.1 - 24.90.29
A Practical Educational Fatigue Testing Machine An experiment and its associated apparatus are proposed to better instill the significanceof the Fatigue Failure Phenomenon in undergraduate engineering education. The benchmark forestablishing the behavior of engineering materials under dynamic/fatigue loading is the “S-N”diagram. Here, “S” corresponds to the stress level and “N” to the number of cycles. Due to theuncertainties involved in material behavior and characteristics, a large number of specimens aretested at different stress levels for generating the “S - log N” diagram. Ideally, the mainobjective in such tests is two-fold. First, to establish (for a given material), up to what stresslevels the material will enjoy an infinite life (Endurance Limit); and second, to correlate thenumber of cycles at different stress levels that a material will be able to go through beforecoming to failure. The range of cost for a typical educational fatigue testing apparatus is from$12,500 to $32,500. These units are essentially adaptations of the R. R. Moore Industrial FatigueTesting Machines which cost in excess of $100,000. The goal is to produce an affordable and afully functional version of the apparatus with less than $3800. The following figures display thepreliminary design of such an apparatus with its first prototype returning promising results. Figure 1. Current Design of the Proposed Figure 2. The First Promising Prototype. Fatigue Testing Machine Figure 3. Pro-E Model of the Loading Linkage. Figure 4. S-N plot based on 7 Tests on 1018-CRS.
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