PSI - Issue 78

Yangwen Zhang et al. / Procedia Structural Integrity 78 (2026) 1008–1015

1011

Fig. 3. (a): Total maximum principal strain at 100% d bd ; (b) Total minimum principal strain at 100% d bd .

Fig. 4. Cycle limit at 25% d bd , 50% d bd , and100% d bd .

2.3. Cumulative damage

To evaluate the low-cycle fatigue performance of the SHARK ® hysteretic damper, a sequential cyclic loading test is planned. The test consists of three displacement levels corresponding to di ff erent amplitudes of the design displacement d bd . Specifically, the damper will be subjected to 50 cycles at 25% d bd ( n 3 = 50), followed by 50 cycles at 50% d bd ( n 2 = 50), and finally 100 cycles at 100% d bd ( n 1 = 100). This test protocol is designed to investigate the damper’s response under progressively increasing strain amplitudes and reflects the requirements of EN 15129 to check the fatigue resistance of the device in the low-cycle regime. To quantify fatigue damage accumulation throughout the entire test, Miner’s rule is employed. This rule estimates cumulative damage D as the sum of damage fractions incurred at each cycle, whose equation can be written as below:

k i = 1

n i N i

D =

(3)

where n i is the number of applied cycles at a given strain amplitude, and N i is the number of cycles to failure at that amplitude, determined from the strain-life curve (see Fig.4 (b)).