Compilation of Multiaxial Load Spectra for Fatigue Durability of Special Vehicle Based on Extreme Value Extrapolation

doi:10.12382/bgxb.2023.0431

Abstract

Abstract:

The service load spectrum of off-road special vehicle is the key to the structural durability of the vehicle. A method for compiling the multiaxial load spectra for the fatigue durability of special vehicle based on extreme value extrapolation is proposed. Considering the phase relationship between the load channels during the extrapolation of multiaxial load spectra, the equivalent synthesis of multiaxial loads based on the critical plane damage parameter is studied. A multiaxial extrapolation model for the exceedance of extreme value being subjected to the generalized Pareto distribution is extablished. The load spectra are extrapolated using the equivalent synthesized load spectra, and the extrapolated variation is allocated to each load channel based on the synthesis coefficient to achieve the multiaxial load extrapolation considering the phase relationship. The multiaxial extrapolation is conducted by taking the six-directional force signal at the wheel center of special vehicles under typical working conditions as the objective. The aspects of the load spectra before and after extrapolation and the load spectra acquisited are all compared in terms of phase relationship, level crossing counting, rainflow counting and power spectral density. The results indicate that the multiaxial load compilation of special vehicle fatigue durability based on extreme value extrapolation can be used to effectively predict the multiaxial load spectra under the same typical working conditions.

Key words: special vehicle, multiaxial load spectra, extreme extrapolation, phase relationship

CLC Number:

TJ306

ZHENG Guofeng, YANG Siyu, CHEN Baixian, WEI Hanbing, ZHAO Shu’en. Compilation of Multiaxial Load Spectra for Fatigue Durability of Special Vehicle Based on Extreme Value Extrapolation[J]. Acta Armamentarii, 2024, 45(7): 2414-2425.

Figures/Tables 14

Fig.1 Schematic diagram of structural fatigue damage calculation based on equivalent stress

Fig.2 Schematic diagram of data processing and methods for random load extrapolation

Fig.3 Load spectrum acquisition of special vehicle fatigue durability

Fig.4 Fatigue durability load spectra of special vehicle

Fig.5 Coefficient of equivalent load spectra and corresponding pseudo damage

Fig.6 Upper and lower exceedances of load spectra and the parameter fitting of generalized Pareto distribution function

Table 1 Upper and lower thresholds and corresponding generalized Pareto distribution parameters

阈值	形状参数	尺度参数
-5471	0.405	731.182
-29673	0.006	2574.500

Fig.7 Extrapolated and captured load spectra

Fig.8 Schematic diagram for calculating the phase relationship of load spectra

Fig.9 Phase relationship matrix of load spectra before and after extrapolation

Fig.10 The level crossing of two load spectra before and after extrapolation

Table 2 The CD between different load spectra and channels

载荷通道	原始载荷谱-外推载荷谱	外推载荷谱-采集载荷谱
F_x	0.9999	0.9928
F_y	0.9990	0.8615
F_z	0.9996	0.9723
M_x	0.9993	0.8965
M_y	0.9989	0.9574
M_z	0.9999	0.9909

Fig.11 Power spectrum density of load spectra before and after extrapolated

Fig.12 Rainflow counting of load spectra before and after extrapolation

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