Fatigue Behavior of M20 Torque Shear High-Strength Bolts under Constant-Amplitude Loading
Abstract
:1. Introduction
2. Experimental Study
2.1. Specimen Design
2.1.1. M20 Torque Shear High-Strength Bolts
2.1.2. T-Shaped Connector
2.2. Material Testing
2.3. Testing-Rig and Loading Procedure
2.4. Experimental Results
3. Numerical Study
3.1. Development of Finite Element Model
3.2. Numerical Results
4. The Calculation Method for Constant-Amplitude Fatigue
4.1. Allowable Nominal Stress Amplitude
4.2. Allowable Hot-Spot Stress Amplitude
4.3. Results and Discussion
5. Comparison of Existing Design Specifications
6. Fatigue Fracture Analysis
7. Concluding Remarks
- (1)
- The fatigue performance, stress concentration and fracture analysis were analyzed. The allowable nominal stress amplitude of M20 torque-shear type high-strength bolts was 96.371 MPa, while the allowable hot-spot stress amplitude was 283.296 MPa.
- (2)
- Upon comparison, it was found that the allowable stress amplitude of M20 torque shear high-strength bolts is twice the design value obtained from ANSI/AISC 360-16 (2016), and 1.93 times the design value obtained from Eurocode 3 (2005) and GB 50017 (2017). These indicate that the existing design standards are relatively conservative for predicting the fatigue performance of such bolts.
- (3)
- A finite element model was established, and the corresponding hot-spot stress and the amplitude of such bolts were obtained. The numerical results suggested that the maximum stress for each bolt was located at the root of the first exposed thread according to the stress nephogram. The fracture positions of the bolts were the same as those of the experimental results.
- (4)
- Fatigue fracture analysis was conducted, and the influence of stress amplitude on the fatigue fracture of high-tensile bolts was evaluated by analyzing the fatigue fracture under different stress amplitudes. The results suggested that the stress amplitude of M20-1, M20-3 and M20-10 was 351.02 MPa, 279.59 MPa and 112.25 MPa, respectively.
- (5)
- The S-N curve of torque-shear high strength bolts under constant-amplitude loading was proposed using the hot-spot stress amplitudes.
8. Future Works
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Specimen No. | Strength (MPa) | Elastic Modulus (GPa) | Elongation Rate | Shrinkage Rate | ||||||
---|---|---|---|---|---|---|---|---|---|---|
δ(%) | (%) | ψ(%) | (%) | |||||||
M20-a | 1016.4 | 1022.4 | 1090.4 | 1097.1 | 209.6 | 208.6 | 10.0 | 10.8 | 42.2 | 42.3 |
M20-b | 1028.1 | 1094.3 | 205.7 | 10.3 | 42.1 | |||||
M20-c | 1022.6 | 1106.7 | 210.6 | 12.2 | 42.7 |
Serial No. | Tension (kN) | Nominal Stress (MPa) | Stress Amplitude (MPa) | Frequency (Hz) | Number of Cycles | ||||
---|---|---|---|---|---|---|---|---|---|
Fmax | Fmin | σmax | σmin | N (×104) | lg(N) | ||||
1 | 123 | 37 | 502.04 | 151.02 | 351.02 | 2.545 | 5 | 2.1068 | 4.324 |
2 | 123 | 37 | 502.04 | 151.02 | 351.02 | 2.545 | 5 | 3.2280 | 4.509 |
3 | 98 | 29.5 | 400.00 | 120.41 | 279.59 | 2.447 | 5 | 6.0624 | 4.783 |
4 | 98 | 29.5 | 400.00 | 120.41 | 279.59 | 2.447 | 5 | 6.5227 | 4.814 |
5 | 73.5 | 22 | 300.00 | 89.80 | 210.20 | 2.323 | 5 | 22.5973 | 5.354 |
6 | 73.5 | 22 | 300.00 | 89.80 | 210.20 | 2.323 | 5 | 16.4380 | 5.216 |
7 | 49 | 14.75 | 200.00 | 60.20 | 139.80 | 2.145 | 7 | 55.8406 | 5.747 |
8 | 49 | 14.75 | 200.00 | 60.20 | 139.80 | 2.145 | 7 | 86.3280 | 5.936 |
9 | 39.25 | 11.75 | 160.20 | 47.96 | 112.24 | 2.050 | 7 | 167.3545 | 6.224 |
10 | 39.25 | 11.75 | 160.20 | 47.96 | 112.24 | 2.050 | 7 | 179.5946 | 6.254 |
Serial No. | Nominal Stress (MPa) | Hot-Spot Stress (MPa) | Nominal Stress Amplitude (MPa) | Hot-Spot Stress Amplitude (MPa) | Number of Cycles | |||||
---|---|---|---|---|---|---|---|---|---|---|
σmax | σmin | max | min | N (×104) | lg(N) | |||||
1 | 502.04 | 151.02 | 808.39 | 243.33 | 351.02 | 2.54 | 565.05 | 2.75 | 2.66 | 4.42 |
2 | 400.00 | 120.41 | 644.04 | 194.03 | 279.59 | 2.44 | 450.00 | 2.65 | 6.29 | 4.79 |
3 | 300.00 | 89.80 | 482.97 | 144.73 | 210.20 | 2.32 | 338.24 | 2.52 | 19.51 | 5.29 |
4 | 200.00 | 60.20 | 322.07 | 97.10 | 139.80 | 2.14 | 224.97 | 2.35 | 71.08 | 5.85 |
5 | 160.20 | 47.96 | 258.10 | 77.39 | 112.24 | 2.05 | 180.71 | 2.25 | 173.47 | 6.24 |
Type of Bolts | S-N Equation | 2×106 | 2×106 |
---|---|---|---|
M20 bolts used in this study | lg(N) = 13.633 − 3.613lg() ± 0.165 | 96.37 | 283.29 |
M20 bolts [1] | lg(N) = 13.2414 − 3.4483lg() ± 0.578 | 70.04 | 304.69 |
M30 bolts [2] | lg(N) = 12.2205 − 3.0872lg() ± 0.4554 | 58.91 | 256.26 |
M39 bolts [2] | lg(N) = 10.8511 − 2.5131lg() ± 0.5028 | 40.82 | 177.57 |
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Zhang, L.; Lei, H.; Shen, Y.; Zhang, S.; Zhou, Z. Fatigue Behavior of M20 Torque Shear High-Strength Bolts under Constant-Amplitude Loading. Buildings 2023, 13, 367. https://doi.org/10.3390/buildings13020367
Zhang L, Lei H, Shen Y, Zhang S, Zhou Z. Fatigue Behavior of M20 Torque Shear High-Strength Bolts under Constant-Amplitude Loading. Buildings. 2023; 13(2):367. https://doi.org/10.3390/buildings13020367
Chicago/Turabian StyleZhang, Liang, Honggang Lei, Yu Shen, Shujia Zhang, and Zichun Zhou. 2023. "Fatigue Behavior of M20 Torque Shear High-Strength Bolts under Constant-Amplitude Loading" Buildings 13, no. 2: 367. https://doi.org/10.3390/buildings13020367