Analysis of Rotor Robustness of Ultra-high Speed Switched Reluctance Machines over 1 Million rpm Using Cohesive Zone Model

2018 ◽  
Author(s):  
Cheng Gong ◽  
Sufei Li ◽  
Thomas G. Habetler
Keyword(s):  
Cohesive Zone ◽  
High Speed ◽  
Cohesive Zone Model ◽  
Zone Model ◽  
Switched Reluctance ◽  
Switched Reluctance Machines ◽  
Ultra High Speed

Multiscale cohesive zone modeling and simulation of high-speed impact, penetration, and fragmentation

2018 ◽  
Vol 03 (01n02) ◽  
pp. 1850003
Author(s):  
Chao Wang ◽  
Dandan Lyu
Keyword(s):  
Cohesive Zone ◽  
High Speed ◽  
Cohesive Zone Model ◽  
Bulk Material ◽  
Cohesive Zone Modeling ◽  
Zone Model ◽  
Spall Fracture ◽  
Weak Formulation ◽  
High Speed Impact ◽  
Different Characteristics

In this work, a multiscale cohesive zone model (MCZM) is developed to simulate the high-speed penetration induced dynamic fracture process such as fragmentation in crystalline solids. This model describes bulk material as a local quasi-continuum medium which follows the Cauchy–Born rule while cohesive zone element is governed by an interface depletion potential, such that the cohesive zone constitutive descriptions are genetically consistent with that of bulk element. This multiscale method proved to be effective in describing material inhomogeneities and it is constructed and implemented in a cohesive finite element Galerkin weak formulation. Numerical simulations of high-speed penetration with different shape of penetrators, i.e., square, circle and parabola nose penetrators are performed. Results show that the proposed MCZM can successfully capture spall fracture, the penetration process and different characteristics of fragmentation under different shape of penetrators.

Application of Multiscale Cohesive Zone Model to Simulate Fracture in Polycrystalline Solids

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Jing Qian ◽  
Shaofan Li
Keyword(s):  
Material Properties ◽  
Cohesive Zone ◽  
High Speed ◽  
Cohesive Zone Model ◽  
Small Scale ◽  
Zone Model ◽  
Transgranular Fracture ◽  
Spall Fracture ◽  
High Speed Impact ◽  
Polycrystalline Solids

In this work, we apply the multiscale cohesive method (Zeng and Li, 2010, “A Multiscale Cohesive Zone Model and Simulations of Fracture,” Comput. Methods Appl. Mech. Eng., 199, pp. 547–556) to simulate fracture and crack propagations in polycrystalline solids. The multiscale cohesive method uses fundamental principles of colloidal physics and micromechanics homogenization techniques to link the atomistic binding potential with the mesoscale material properties of the cohesive zone and hence, the method can provide an effective means to describe heterogeneous material properties at a small scale by taking into account the effect of inhomogeneities such as grain boundaries, bimaterial interfaces, slip lines, and inclusions. In particular, the depletion potential of the cohesive interface is made consistent with the atomistic potential inside the bulk material and it provides microstructure-based interface potentials in both normal and tangential directions with respect to finite element boundary separations. Voronoi tessellations have been utilized to generate different randomly shaped microstructure in studying the effect of polycrystalline grain morphology. Numerical simulations on crack propagation for various cohesive strengths are presented and it demonstrates the ability to capture the transition from the intergranular fracture to the transgranular fracture. A convergence test is conducted to study the possible size-effect of the method. Finally, a high-speed impact example is reported. The example demonstrates the advantages of multiscale cohesive method in simulating the spall fracture under high-speed impact loads.

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