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In this paper, small blocks of 17-4 PH stainless steel were manufactured via extrusion-based bound powder extrusion (BPE)/atomic diffusion additive manufacturing (ADAM) technology in two different orientations. Ultrasonic bending-fatigue and uniaxial tensile tests were carried out on the test specimens prepared from the AM blocks. Specifically, a recently-introduced small-size specimen design is employed to carry out time-efficient fatigue tests. Based on the results of the testing, the stress–life (S-N) curves were created in the very high-cycle fatigue (VHCF) regime. The effects of the printing orientation on the fatigue life and tensile strength were discussed, supported by fractography taken from the specimens’ fracture surfaces. The findings of the tensile test and the fatigue test revealed that vertically-oriented test specimens had lower ductility and a shorter fatigue life than their horizontally-oriented counterparts. The resulting S-N curves were also compared against existing data in the open literature. It is concluded that the large-sized pores (which originated from the extrusion process) along the track boundaries strongly affect the fatigue life and elongation of the AM parts.
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A Thermodynamic Framework for Rapid Prediction of S-N Curves Using Temperature Rise at Steady-State
Abstract Building S-N curves for materials traditionally involves conducting numerous fatigue tests, resulting in a time- consuming and expensive experimental procedure that can span several weeks. Thus, there is a need for a more efficient approach to extract the S-N curves. The primary purpose of this research is to propose a reliable approach in the framework of thermodynamics for the rapid prediction of fatigue failure at different stress levels. The proposed method aims to offer a simple and efficient means of extracting the S-N curve of a material. A method is introduced based on the principles of thermodynamics. It uses the fracture fatigue entropy (FFE) threshold to estimate the fatigue life by conducting a limited number of cycles at each stress level and measuring the temperature rise during the steady-state stage of fatigue. An extensive set of experimental results with carbon steel 1018 and SS 316 are conducted to illustrate the utility of the approach. Also, the efficacy of the approach in characterizing the fatigue in axial and bending loadings of SAE 1045 and SS304 specimens is presented. It successfully predicts fatigue life and creates the S-N curves. The effectiveness of the approach is evaluated successfully for different materials under different loading types. The results show that the temperature rise is an indicator of the severity of fatigue and can be used to predict life.
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- Award ID(s):
- 2052810
- PAR ID:
- 10518717
- Publisher / Repository:
- SEM
- Date Published:
- Journal Name:
- Experimental Mechanics
- Volume:
- 64
- Issue:
- 2
- ISSN:
- 0014-4851
- Page Range / eLocation ID:
- 167 to 180
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/s11340-023-01016-y
