The Fatigue Damaging Effect of a Random Load

2009 ◽  
pp. 45-45-9 ◽  
Author(s):  
Waloddi Weibull
Keyword(s):  
Random Load

Bending fatigue of single-wall and double-wall corrugated paperboards under sinusoidal and random loads

2021 ◽  
pp. 109963622110204
Author(s):  
Zhi-Wei Wang ◽  
Yang-Zhou Lai ◽  
Li-Jun Wang
Keyword(s):  
Energy Dissipation ◽  
Fatigue Failure ◽  
Fatigue Tests ◽  
Stiffness Degradation ◽  
Random Load ◽  
Bending Fatigue ◽  
Random Loads ◽  
Vibration Fatigue ◽  
Sinusoidal Load ◽  
Double Wall

The bending fatigue tests of single-wall and double-wall corrugated paperboards were conducted to obtain the εrms– N curves under sinusoidal and random loads in this paper. The εrms– N equation of corrugated paperboard can be described by modified Coffin–Manson model considering the effect of mean stress. Four independent fatigue parameters are obtained for single-wall and double-wall corrugated paperboards. The εrms– N curve under random load moves left and rotates clockwise compared with that under sinusoidal load. The fatigue life under random load is much less than that under sinusoidal load, and the fatigue design of corrugated box should be based on the fatigue result under random load. The stiffness degradation and energy dissipation of double-wall corrugated paperboard before approaching fatigue failure are very different from that of single-wall one. For double-wall corrugated paperboard, two turning points occur in the stiffness degradation, and fluctuation occurs in the energy dissipation. Different from metal materials, the bending fatigue failure of corrugated paperboard is a process of wrinkle forming, spreading, and folding. The results obtained have practical values for the design of vibration fatigue of corrugated box.

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.

ESTIMATION OF THE FAILURE PROBABILITY OF A REINFORCED CONCRETE BEAM LYING ON A STOCHASTIC ELASTIC BASE WITH TWO PRESSURE COEFFICIENTS, ON AN INCLINED SECTION FROM THE LATERAL FORCE

2021 ◽  
Vol 93 (1) ◽  
pp. 16-25
Author(s):  
P.D. DEMINOV ◽  
Keyword(s):  
Reinforced Concrete ◽  
Failure Probability ◽  
Rational Functions ◽  
Lateral Force ◽  
Elastic Base ◽  
Strength Properties ◽  
Reinforced Concrete Beams ◽  
Total Probability ◽  
Limit States ◽  
Random Load

The estimate of failure probability on the inclined section from the action of transverse forces, as well as the total probability of the limit States of reinforced concrete beams with probabilistic strength parameters lying on an elastic Foundation model V.Z. Vlasov-P.L. Pasternak, possessing stochastic properties. Probabilistic characteristics of the transverse force and its distribution density are constructed for a Foundation beam resting on an elastic base with two random characteristics, loaded with a quasi-stationary random load, taking into account the probabilistic nature of the strength properties of concrete and reinforcement. It is shown that if the spectral densities of the bed and load coefficients are fractional rational functions, the deflection correlation functions and, accordingly, the deflection variance are calculated using the residue theory.

scholarly journals Reliability and Random Lifetime Models of Planetary Gear Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Peng Gao ◽  
Liyang Xie ◽  
Wei Hu
Keyword(s):  
Load Distribution ◽  
Planetary Gear ◽  
Working Process ◽  
Random Load ◽  
Working Mechanism ◽  
Dynamic Reliability ◽  
Reliability Models ◽  
Process Failure ◽  
Failure Dependence ◽  
Gear Systems

Conventional reliability models of planetary gear systems are mainly static. In this paper, dynamic reliability models and random lifetime models of planetary gear systems are developed with dynamic working mechanism considered. The load parameters, the geometric parameters, and the material parameters are taken as the inputs of the reliability models and the random lifetime models. Moreover, failure dependence and dynamic random load redistributions are taken into account in the models. Monte Carlo simulations are carried out to validate the proposed models. The results show that the randomness of the load distribution is obvious in the system working process. Failure dependence has significant influences on system reliability. Moreover, the dispersion of external load has great impacts on the reliability, lifetime distribution, and redundancy of planetary gear systems.

scholarly journals Spectral analysis of vibration in weakly non-linear systems

2000 ◽  
Vol 22 (3) ◽  
pp. 181-192
Author(s):  
Nguyen Tien Khiem
Keyword(s):  
Nonlinear Systems ◽  
Spectral Density ◽  
Density Function ◽  
Asymptotic Methods ◽  
Random Excitation ◽  
Spectral Density Function ◽  
Kolmogorov Equation ◽  
Spectral Structure ◽  
Random Load ◽  
Weakly Nonlinear

The weakly nonlinear systems subjected to deterministic excitations have been fully and deeply studied by use of the well developed asymptotic methods [1-4]. The systems excited by a random load have been investigated mostly using the Fokker-Plank-Kolmogorov equation technique combined with the asymptotic methods [5-8]. However, the last approach in most successful cases allows to obtain only a stationary single point probability density function, that contains no information about the correlation nor' consequently, the spectral structure of the response. The linearization technique [9, 10] in general permits the spectral density of the response to be determined, but the spectral function obtained by this method because of the linearization eliminates the effect of the nonlinearity. Thus, spectral structure of response of weakly nonlinear systems to random excitation, to the author's knowledge, has not been studied enough. This paper deals with the above mentioned problem. The main idea of this work is the use of an analytical simulation of random excitation given by its spectral density function and afterward application of the well known procedure of the asymptotic method to obtain an asymptotic expression of the response spectral density function. The obtained spectral relationship covers the linear system case and especially emphasizes the nonlinear effect on the spectral density of response. The theory will be illustrated by an example and at the end of this paper there will be a discussion about the obtained results.  

scholarly journals Modeling active fault systems and seismic events by using a fiber bundle model – example case: the Northridge aftershock sequence

Solid Earth ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 1519-1540
Author(s):  
Marisol Monterrubio-Velasco ◽  
F. Ramón Zúñiga ◽  
José Carlos Carrasco-Jiménez ◽  
Víctor Márquez-Ramírez ◽  
Josep de la Puente
Keyword(s):  
Fiber Bundle ◽  
Active Faults ◽  
Aftershock Sequence ◽  
Statistical Characteristics ◽  
Real Sequence ◽  
Random Load ◽  
Fault Systems ◽  
Aftershock Sequences ◽  
Fiber Bundle Model ◽  
Initial Load

Abstract. Earthquake aftershocks display spatiotemporal correlations arising from their self-organized critical behavior. Dynamic deterministic modeling of aftershock series is challenging to carry out due to both the physical complexity and uncertainties related to the different parameters which govern the system. Nevertheless, numerical simulations with the help of stochastic models such as the fiber bundle model (FBM) allow the use of an analog of the physical model that produces a statistical behavior with many similarities to real series. FBMs are simple discrete element models that can be characterized by using few parameters. In this work, the aim is to present a new model based on FBM that includes geometrical characteristics of fault systems. In our model, the faults are not described with typical geometric measures such as dip, strike, and slip, but they are incorporated as weak regions in the model domain that could increase the likelihood to generate earthquakes. In order to analyze the sensitivity of the model to input parameters, a parametric study is carried out. Our analysis focuses on aftershock statistics in space, time, and magnitude domains. Moreover, we analyzed the synthetic aftershock sequences properties assuming initial load configurations and suitable conditions to propagate the rupture. As an example case, we have modeled a set of real active faults related to the Northridge, California, earthquake sequence. We compare the simulation results to statistical characteristics from the Northridge sequence determining which range of parameters in our FBM version reproduces the main features observed in real aftershock series. From the results obtained, we observe that two parameters related to the initial load configuration are determinant in obtaining realistic seismicity characteristics: (1) parameter P, which represents the initial probability order, and (2) parameter π, which is the percentage of load distributed to the neighboring cells. The results show that in order to reproduce statistical characteristics of the real sequence, larger πfrac values (0.85<πfrac<0.95) and very low values of P (0.0<P≤0.08) are needed. This implies the important corollary that a very small departure from an initial random load configuration (computed by P), and also a large difference between the load transfer from on-fault segments than by off-faults (computed by πfrac), is required to initiate a rupture sequence which conforms to observed statistical properties such as the Gutenberg–Richter law, Omori law, and fractal dimension.

Processing Load Signal on Wheel Loader Transmission

2011 ◽  
Vol 383-390 ◽  
pp. 4482-4485
Author(s):  
Li Sun ◽  
Yong Chen Liu
Keyword(s):  
Time Course ◽  
Load Spectrum ◽  
Processing Load ◽  
Random Load ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Wheel Loader ◽  
Virtual Test ◽  
Low Pass ◽  
Filter Frequency

To determine fatigue life of Loader transmission and to analyze machine power for different user, the torque loads of wheel loader transmission are tested and calibrated with the method of four sections per cycle. The disturbed signals are filtered by low-passed filter, and anomalous spikes are eliminated with the NSOFT. And contrastively analyzes the disposal effect of signal, then acquires pure random load-time course. It concludes that one Hz of the low-pass filter frequency is suitable, and the test signal is in line with the actual work of Loader. These provide the base for getting load spectrum and virtual test on wheel loader transmission.

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