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A nonlinear friction-cohesive model for characterizing mode II fracture of laminated composites
Ruoyu Li,Chaocan Cai,Zhonghai Xu,Xiaocan Zou,Chunxing Hu,Xiaodong He 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.5
In this paper, the Coulomb friction is incorporated into the exponential cohesive law, so a nonlinear friction-cohesive model combining sliding friction and interfacial debonding is developed to characterize the mechanical responses of mode II fracture. This model can well simulate the load-displacement curve of ENF test, after properly calibrating the parameters through the experimental data available in the literature. Then, a parametric study to investigate the effects of interfacial parameters on the load-displacement curves of ENF test has been carried out. The results show that, compared with the bi-linear cohesive model and exponential cohesive model, the proposed model is closer to the experimental data. Friction parameters will affect the initial delamination stage and stable delamination stage of ENF test, and interfacial characteristic lengths and interfacial shear strength will affect the peak load of ENF test.
Analysis of Traffic Splitting Mechanisms for 2D Mesh Sensor Networks
Huimin She,Zhonghai Lu,Axel Jantsch,Li-Rong Zheng,Dian Zhou 보안공학연구지원센터 2008 International Journal of Software Engineering and Vol.2 No.3
For many applications of sensor networks, it is essential to ensure that messages are transmitted to their destinations within delay bounds and the buffer size of each sensor node is as small as possible. In this paper, we firstly introduce the system model of a mesh sensor network. Based on this system model, the expressions for deriving the delay bound and buffer requirement bound are presented using network calculus theory. In order to balance traffic load and improve resource utilization, three traffic splitting mechanisms are proposed. And the two bounds are derived in these traffic splitting mechanisms. To show how our method applies to real applications, we conduct a case study on a fresh food tracking application, which monitors the food freshness status in real-time during transportation. The numerical results show that the delay bound and buffer requirement bound are reduced while applying traffic splitting mechanisms. Thus the performance of the whole sensor network is improved with less cost.
Chunxing Hu,Yujiao Bai,Zhonghai Xu,Ruoyu Li,Rongguo Wang,Xiaodong He 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.9
Composite laminates often produce delamination due to a series of factors during the manufacture and service process. In order to research the effect of containing oblique elliptical and circular initial delamination damage on the compressive strength of composite laminates, numerical and experimental methods are used in this paper. Finite element models (FEMs) and the progressive damage subroutine USDFLD are developed to predict the damage initiation and extension behavior of the intralaminar of the laminate. Interlaminar damage is predicted based on cohesive zone models (CZM). At the same time, four compression tests containing different initial delamination damage are performed. The results show that experimental measurements of compression tests concur with the numerical predictions and validate the FEMs. The strength and stiffness of the specimens gradually decrease with the increase of the initial delamination area. It reveals that, for the compression process, the delamination damage extends from the edge of the initial damage to the surroundings. The bearing capacity of the composite laminates is mainly determined by the material properties of the fibers and matrix, rather than the initial delamination.