Get This Paper

Block Fatigue Testing Techniques Considering Hold Time, Frequency, and Residual Stress-Strain Curves


Title: Block Fatigue Testing Techniques Considering Hold Time, Frequency, and Residual Stress-Strain Curves

Authors: Ethan P. Ficker, Mitchel A. Bergmann, Jackson L. Morgan, Eric Kerr-Anderson

DOI: 10.33599/nasampe/c.23.0176

Abstract: Block fatigue testing is a technique that can be used to accelerate the damage accumulation of a specimen by using high load tensile-tensile fatigue first to consume a certain percentage of the fatigue life of a specimen prior to dropping to a lower load to failure. Damage accumulation theory allows for partial life consumption analysis which would provide a simple percentage based extrapolation to generate a S-N curve in a fraction of the time of a traditional fatigue testing campaign. Results from previous testing demonstrated that such a methodology correlates with a correction multiplier. In order to better understand the effect of block testing, three additional aspects were examined. The use of a hold time between blocks in order to allow for polymer chain relaxation prior to resuming fatigue testing at a lower tensile load. Traditional S-N curve generation can rely on a constant frequency, which would result in a slightly different strain rate at different max-min loading combinations due to more displacement in the same cycle time. This aspect was examined by using block testing at the same loads with different frequencies. The final damage mechanism that was examined was how the stress-strain curve changed as a function of fatigue life. These experiments provided additional insight into the possible use of block fatigue testing to accelerate meaningful fatigue curve generation.

References: [1] Eftekhari, Mohammadreza, & Fatemi, Ali. “Creep-Fatigue Interaction and Thermo-Mechanical Fatigue Behaviors of Thermoplastics and Their Composites.” Vol. 91. International Journal of Fatigue, 2016, pp. 136–148, [2] Everaerts, Joris, Gontcharov, Denis, Verlinden, Bert, & Wevers, Martine. “The Influence of Load Holds on the Fatigue Behaviour of Drawn Ti-6al-4v Wires.” International Journal of Fatigue, vol. 98, 2017, pp. 203–211, [3] Eftekhari, Mohammadreza, & Fatemi, Ali. “On the Strengthening Effect of Increasing Cycling Frequency on Fatigue Behavior of Some Polymers and Their Composites: Experiments and Modeling.” International Journal of Fatigue, vol. 87, 2016, pp. 153–166, [4] Zhao, Gaole, Qi, Hongyu, Li, Shaolin, Yang, Xiaoguang, & Shi, Duoqi. “Effects of Tensile Load Hold Time on the Fatigue and Corrosion-Fatigue Behavior of Turbine Blade Materials.” International Journal of Fatigue, vol. 152, 2021, pp. 106–448, [5] Bolotin, Vladimir V. Mechanics of Fatigue. Boca Raton, FL: CRC Press, 2020. [6] Pegoretti, Alessandro, & Ricco, Theonis. “Fatigue Fracture of Neat and Short Glass Fiber Reinforced Polypropylene: Effect of Frequency and Material Orientation.” Journal of Composite Materials, vol. 34, no. 12, 2000, pp. 1009–1027, [7] Haque, Md Minhaz-Ul, Goda, Koichi, Ogoe, Shinji, & Sunaga, Yuta. “Fatigue analysis and fatigue reliability of polypropylene/wood flour composites.” Advanced Industrial and Engineering Polymer Research, vol. 2, no. 3, 2019, pp. 136–142, [8] Johnson, Sarah E. & Kerr-Anderson, Eric. “Accelerated Tensile-Tensile Fatigue Testing of Long Fiber Thermoplastic Materials.” Winona State University, 2022.

Conference: CAMX 2023

Publication Date: 2023/10/30

SKU: TP23-0000000176

Pages: 15

Price: $30.00

Get This Paper