The effect of load sequence on GRMS measurements

2002 ◽  
Author(s):  
B.P. Marquis ◽  
H. Weinstock ◽  
G. Carr ◽  
R. Greif
Keyword(s):  
Load Sequence

scholarly journals Effect of load sequence interaction on bond-wire lifetime due to power cycling

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zoubir Khatir ◽  
Son-Ha Tran ◽  
Ali Ibrahim ◽  
Richard Lallemand ◽  
Nicolas Degrenne
Keyword(s):  
High Stress ◽  
Bipolar Transistors ◽  
Junction Temperature ◽  
Experimental Investigations ◽  
Power Cycling ◽  
Power Modules ◽  
Bond Wire ◽  
Load Sequence ◽  
The Difference ◽  
Heating Duration

AbstractExperimental investigations on the effects of load sequence on degradations of bond-wire contacts of Insulated Gate Bipolar Transistors power modules are reported in this paper. Both the junction temperature swing ($$\Delta T_{j}$$ Δ T j ) and the heating duration ($$t_{ON}$$ t ON ) are investigated. First, power cycling tests with single conditions (in $$\Delta T_{j}$$ Δ T j and $$t_{ON}$$ t ON ), are performed in order to serve as test references. Then, combined power cycling tests with two-level stress conditions have been done sequentially. These tests are carried-out in the two sequences: low stress/high stress (LH) and high stress/low stress (HL) for both $$\Delta T_{j}$$ Δ T j and $$t_{ON}$$ t ON . The tests conducted show that a sequencing in $$\Delta T_{j}$$ Δ T j regardless of the direction “high-low” or “low–high” leads to an acceleration of degradations and so, to shorter lifetimes. This is more pronounced when the difference between the stress levels is large. With regard to the heating duration ($$t_{ON}$$ t ON ), the effect seems insignificant. However, it is necessary to confirm the effect of this last parameter by additional tests.

scholarly journals Improved numerical model for fatigue cumulative damage of mechanical structure considering load sequence and interaction

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199530
Author(s):  
Bixiong Huang ◽  
Shuci Wang ◽  
Shuanglong Geng ◽  
Xintian Liu
Keyword(s):  
Fatigue Life ◽  
Theoretical Basis ◽  
Life Prediction ◽  
Damage Model ◽  
Cumulative Damage ◽  
Load Spectrum ◽  
Random Load ◽  
Mechanical Parts ◽  
Proposed Model ◽  
Load Sequence

To more accurately predict the fatigue life of components under the action of random loads, it is necessary to explore the influence of the interaction between the load sequence and the load on the life prediction. Based on the Manson-Halford method and Corten-Dolan model, this paper establishes a fatigue cumulative damage model that takes into account both the load order and the interaction between loads, and also takes into account the loads near the fatigue limit. The fatigue life of mechanical parts under random load can be calculated through this model, which provides a theoretical basis for life prediction under random load spectrum. The fatigue life of mechanical parts under random load can be calculated through this model, which provides a theoretical basis for life prediction under random load spectrum. Comparing the calculation results of the proposed model with the results of Palmgren Miner, Manson-Halford method, and Corten-Dolan model, it is found that the fatigue damage model established can reasonably predict the fatigue life of parts. Comparison and verification of examples further prove the accuracy and reliability of the proposed model.

Finite Element Study of the Effect of Load Sequence on the Fretting Wear

2020 ◽  
Author(s):  
Pankaj Dhaka ◽  
Raghu V. Prakash
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fretting Wear ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Low Load ◽  
Dimensional Finite Element ◽  
Wear Modelling ◽  
Load Sequence ◽  
Contact Parameters

Abstract Understanding the effect of load sequence is important in the context of a blade-disc dovetail joint in an aero-engine and many other such applications where, the mating surfaces undergo fretting wear under variable slip amplitude loading conditions. In the present work, a two-dimensional finite element analysis is carried out for a cylinder-on-plate configuration. The cylinder is modeled as deformable whereas the plate is modelled as rigid. An incremental wear modelling algorithm is used to model the wear of cylindrical pad while the plate is assumed as un-worn. This simulates a practical scenario where, generally one of the mating surfaces is sufficiently hardened or an interfacial harder/sacrificial element is inserted to restrict the wear to only one of the surfaces. A Fortran-based ABAQUS® subroutine UMESHMOTION is used to simulate the wear profile for the cylinder. A constant extrapolation technique is used to simulate 18000 cycles of fretting. The finite element analysis results are validated with the analytical solutions and literature data. The fretting wear modelling is carried out for two different slip amplitudes viz., 25 μm and 150 μm, to simulate the low and high slip amplitude loading respectively. Two blocks of alternate low and high slip amplitudes are applied to understand the influence of load sequence. Important contact parameters viz., contact pressure, contact stresses and contact slip are extracted. A comparison is made between the low-high and high-low load sequence based on the contact tractions and worn out profiles.

LOAD SEQUENCE ANALYSIS IN FATIGUE LIFE PREDICTION

2015 ◽  
Vol 39 (4) ◽  
pp. 819-828 ◽  
Author(s):  
Moises Jimenez ◽  
Jose Martinez ◽  
Ulises Figueroa
Keyword(s):  
Life Prediction ◽  
Rear Axle ◽  
Element Analysis ◽  
Proposed Model ◽  
Damage Process ◽  
Load Sequence ◽  
Number Of Cycles ◽  
Total Damage ◽  
Damage Rule

In this work, the load sequence effect is analyzed in fatigue test. One of the assumptions of the Miner’s rule is that the total damage is equal to the sum of the damages absorbed; however, different models have been proposed to take the effect of the load sequences under two load levels into account. To analyze this effect, a case study of a rear axle mounting bracket has been performed, analyzing six different sequences of three load levels, defined as Low, Medium and High. A Finite Element Analysis was also performed using MSC Tools. With these results and a series of test at constant amplitude, the component S-N curve was made. 24 tests at room temperature were performed in order to evaluate the damage process. It was found that, under a block of three load levels, the sequence of each block has an effect in the total amount of damage under the same number of cycles. With this information it is possible to improve the life prediction through the modification of the damage rule. The proposed model uses a factor which depends on the ultimate strength and yield point. This is an advantage over other approaches, as the other models need additional dynamic tests to obtain coefficients to perform the life prediction.

A TMF crack propagation model considering time dependency and load sequence effects

2020 ◽  
Vol 237 ◽  
pp. 107218
Author(s):  
Michael Rupp ◽  
Guido Dhondt ◽  
Martin Becker ◽  
Andreas Fischersworring-Bunk ◽  
Antje Rohr ◽  
...  
Keyword(s):  
Crack Propagation ◽  
Propagation Model ◽  
Time Dependency ◽  
Sequence Effects ◽  
Load Sequence

A Method Based on Wavelet Neural Network for Power System Short Term Load Forecasting

2014 ◽  
Vol 521 ◽  
pp. 303-306 ◽  
Author(s):  
Hong Mei Zhong ◽  
Jie Liu ◽  
Qi Fang Chen ◽  
Nian Liu
Keyword(s):  
Neural Network ◽  
Power System ◽  
Bp Neural Network ◽  
Load Forecasting ◽  
Wavelet Neural Network ◽  
Signal Spectrum ◽  
Short Term ◽  
Short Term Load Forecasting ◽  
Load Sequence ◽  
Daily Load

The short-term load of Power System is uncertain and the daily-load signal spectrum is continuous. The approach of Wavelet Neural Network (WNN) is proposed by combing the wavelet transform (WT) and neural network. By the WT, the time-based short-term load sequence can be decomposed into different scales sequences, which is used to training the BP neural network. The short-term load is forecasted by the trained BP neural network. Select the load of a random day in Lianyungang to study, according to the numerical simulation results, the method proves to achieve good performances.

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