A numerical approach to simulate 3D crack propagation in turbine blades

The dynamic model and three-dimensional finite element analytical model of cracked gear structure are established respectively according to the cracked beam theory, and the dynamic characteristics (natural frequency, vibration shape) of cracked gear body are investigated. Further the influences of crack position and crack length on the dynamic characteristics of gear structure are simulated and discussed. On this basis, the fracture and damage of gear structure are investigated according to the theory of fracture mechanics. Using FRANC3D software, the three-dimensional (3D) propagation of crack at tooth root for involute gear is simulated, and stress intensity factor (SIF)s of semi-circular crack at tooth root including three types are analyzed, their variation laws are gained, then the expressions of SIFs are obtained by numerical fitting FEM results. Based on this, the 3D crack propagation path at tooth root is simulated and discussed, then, it is verified by comparing to experimental results, according to the mutation of the maximum SIF at crack tip, the fracture and damage of gear tooth are judged, and its work life also is predicted. These have very important value for damage monitoring and diagnosis of gear.

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Fracture Toughness of Northeast China Larch

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.517.661 ◽

2012 ◽

Vol 517 ◽

pp. 661-668 ◽

Cited By ~ 2

Author(s):

L.P. Qiu ◽

En Chun Zhu ◽

Hua Zhang Zhou ◽

L.Y. Liu

Keyword(s):

Numerical Simulation ◽

Fracture Toughness ◽

Stress Intensity ◽

Crack Propagation ◽

Material Properties ◽

Northeast China ◽

Numerical Approach ◽

Mode I ◽

Mode Ii ◽

Full Size

Wood, as a green and environment-friendly building material, is widely used in building engineering. Naturally grown, wood has various defects like knots, cracks and inclined grain. Fracture Mechanics is thus an efficient tool to investigate the mechanical behavior of wood and wood-based composite products. According to Linear-elastic Fracture Mechanics (LEFM), fracture toughness can be introduced to measure the resistance to crack propagation. Crack was assumed to occur when the stress intensity factorKreached a critical valueKC.Fracture in wood usually involves not only the Mode I type (open) fracture, but also the Mode II type (shear) fracture. For getting a better understanding of the crack growth phenomenon of Northeast China Larch, it is, therefore, essential to assess theKICandKIIC, which are the critical stress intensity factors for Mode I and Mode II type fracture, respectively. In the current study,KICandKIIC, of Northeast China Larch were determined through tests with compact tension specimens and tests with compact symmetric shear specimens, respectively. In addition, the material properties tests were also performed. All of the specimens were cut from the same batch of Glulam beams. Based on the obtained data from experiments, LEFM was employed to explain the fracture failure in the form of crack propagation. Using Extended Finite Element Method (XFEM), simulation of the crack propagation in Mode I and Mode II was performed incorporating ABAQUS. The crack propagation and the load-displacement curves of numerical simulation were in good agreement with experiments, which validated that the proposed numerical approach is suitable for analysis of crack growth in the specimens. As part of a larger program to investigate the fracture behavior of Glulam beams made of Northeast China Larch, this study provides the material properties and validation of the numerical simulation approach. A series of experiments of full-size curved Glulam beams subject to bending and the corresponding simulations extending the numerical approach of this study to the cases of full-size wood composite members are under development.

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Deformation properties of self-adapting wind turbine blades numerical approach and optimization

Thermal Science ◽

10.2298/tsci1904397c ◽

2019 ◽

Vol 23 (4) ◽

pp. 2397-2402

Author(s):

Xiao Chen ◽

Li Qiu ◽

Qiang Cen

Keyword(s):

Power Generation ◽

Wind Speed ◽

Turbine Blades ◽

Numerical Approach ◽

Wind Turbine Blades ◽

Wind Speeds ◽

Mechanics Model ◽

Deformation Properties ◽

Glass Carbon ◽

Flexible Deformation

All wind-driven generators need to be equipped with brakes to ensure operational control and safety. Many methods are available to avoid over-speed of the blower. This paper establishes a mechanics model to investigate each point on turbine blades, which are such designed that they would change shape in high winds to reduce the frontal area through adaptive and flexible deformation. In this way, high wind speeds will cause deformation of the blades and decrease of the rotational speed, as a result the turbine slows down. A numerical analysis of the fluid in the fan housing and a force analysis of the blades are performed, and numerical results are used to design the non-uniform arrangement of the hybrid glass/carbon fiber. A wind tunnel experiment is performed on the new blade design. The experimental results show that the new blade achieves an improvement in its mechanical properties and is able to adaptively adjust the torque. During the operation of the wind-driven generator, the new blade could effectively broaden the operational range of wind speeds, thereby improving the power generation when the wind speed is low. A generator without a brake stalls when the wind speed exceeds 13 m/s. After the adoption of the self-adaptive blade made up of the uniform-section complex textile material, the power set shows reduction of noise, avoidance of blade runaway, improvement of the efficiency of the power generation, decrease of cost and enhancement of blade consistency.

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