Dynamic Analysis of a Deep Groove Ball Bearing Using ... - ethesis

When the rolling element passes through the fault, the shock load is transferred through the bearing part to the surface of the bearing housing. The dynamic analysis of the bearing enables the analysis of the bearing during movement and the calculation of the stress developed in each part of the bearing, as well as the extraction of the vibration signal. In the simulation of the first model, different boundary conditions were specified in ANSYS 15.0 simulation software to find the rotation of the W-6206 2Z bearing model.

The second model with a known defect, made on the inner surface of the outer race, was exposed to the same boundary conditions.

Jewel Bearing

Fluid Bearings

Magnetic Bearing

Flexure Bearing

Ball Bearing

Geometry and Elements of Deep Groove Ball Bearing

In the inner ring and the outer ring, grooves are provided in a guideway for the rolling movement of the balls and which also limit the movement of the balls. A cage is provided to maintain a minimum distance between the balls, to reduce the number of balls, thus reducing the weight of the bearing and to reduce friction by creating a convex-concave contact instead of convex -convex contacts. This type of contact also avoids dents on the balls and thus improves the life of the bearing.

Advantages and Limitations

The main limitation of deep groove ball bearings is the flattened balls over high pressure in the outer ring which can lead to bearing failure.

Objectives

Literature Review

The maximum contact pressure was calculated using the finite element method and was also analyzed in the ball and track contact area to predict the contact pressure. The extraction of the fault characteristic frequency ensures the identification of the bearing fault from the vibration signal of the faulty bearing. Structural and thermal analyzes were performed to reveal the characteristic properties of the bearing.

Bearing performance is mainly characterized by thermal expansion due to friction and stress concentration between the rolling element and the road.

Finite Element Method

In this paper, the finite element method is used with CATIAV6 modeling software and ANSYS 15.0 academic research modeling and analysis software. The following chapter provides the user with a concise understanding of the workspace and its associated methodology and terms, provided the user has some basic modeling knowledge in CATIA V6 and the application of the ANSYS 15.0 Modeling and Analysis module for applying conditions border.

Nonlinear Analysis

Changing Status

Many structures exhibit non-linearity due to the sudden change of status from non-contact to contact, and are therefore status dependent. For example, the behavior of the rope changes from slack to taut, or the rolling surface changes from non-contact to contact.

Geometric Nonlinearities

Material Nonlinearities

M] stands for mass structural matrix [C] stands for structural damping matrix [K] stands for structural stiffness matrix. Nsb stands for the number of sections in an element with stiffness proportional material damping input. Kn j stands for a portion of element j structural stiffness matrix based on section n Ne stands for the number of elements with specified damping.

Types

Stages of Transient Analysis

Build the Model

Fine graining should be done to determine the parameters such as load, deformation, etc. at the region of highest stress concentration. More fine-graining is required in the areas of stress or strain compared to the areas where only displacements are required. The mesh must also be fine enough to resolve the wave propagation effects.

Apply Loads and Obtain the Solution

PREP7 is used to describe element types, real element constants, material properties, and model geometry. To identify the highest mode of interest, a primary model analysis should be performed prior to transient structural analysis. Initial conditions such as initial displacement and initial velocity are essential for transient structural analysis.

When some bodies have zero initial displacement but non-zero constant initial velocity, only bodies can be specified and input constant initial velocity. Time-Varying Loads Structural loads and joint conditions can be entered as time-dependent load histories. When adding a load or joint condition, the magnitude can be defined as a constant, table value, or function.

To specify the dynamic response, it is important to use automatic time stepping, correctly choosing the initial, minimum and maximum time steps accurately. Explicit time integration is used for rigid dynamic analyzes and implicit time integration for transient structural analyses. Its main work is to reduce the total number of time steps by changing the size of time steps, which is based on response frequency and non-linearities.

Automatic time stepping is good for most analyses, but in some cases it is not used.

Review the Results

These designs experienced some bugs, so they were modified and tested many times to find the desired results. Modeling is done in Academic CATIA V6 and ANSYS 15.0 software and then exported to ANSYS 15.0 for simulation.

First Model

Intermediate Models

Final Model

Modelling in ANSYS 15.0

The final model is designed in ANSYS 15.0 itself to solve the contact problem encountered during the simulation process, when the model is imported from CATIA V6 software and designed in two steps, i.e.

Design of bearing

Design of cage

Support System
Model Meshing in ANSYS 15.0
Model with Crack
Scope for Future Research

The second model (fig: 4.11) with a crack in the outer race inner surface in contact with balls was prepared and is listed below. Crack width is 3mm and depth is 1mm in the y direction radially, at a distance of 28.5 mm to 29.5 mm and made on the surface of the outer race, exposed to balls. From five accelerometer probes, data was extracted from probe one exactly above the defect in Y direction for both healthy and faulty bearing.

Which shows signals identical to those obtained by the numerical methods shown in figure: 5.2. The accelerometer shows a false signal when the ball passes through a known fault and is captured on the graph shown in Figure: 5.3. The density of the mixture must be high in the contact zone, which is on the inner surface of the outer ring, the outer surface of the inner ring, the surface of the ball and the surface of the cage (exposed to the balls).

The size of the element in the contact area greatly affects the time required for simulation using the finite element method. Therefore, element size of 1 mm is taken to generate mesh in the contact area. The cage is the necessary element for the rotation of the rolling element (balls) in the deep groove ball holder, otherwise the balls will collapse and the analysis will stop.

Therefore, it can reduce the cost of bearing testing and manufacturing by optimizing bearing parameters from this technique. Therefore, this analysis plays a major role in the field of bearing testing and monitoring.

Figure 4.6: Final design of cage Bearing Finalized model with cage is listed in fig: 4.7

Annexure – A

Modelling

After this, it will appear in the Tree Overview window on the left. Now go to the Details window and set Operation as Add Frozen and the dimensions in Axis Definition as X component 0 mm, Y component 0 mm, Z component 16 mm and Radius 31 mm (fig: A.4 (a)) and it appears (fig: A.4 (b)) in the graphics window, as shown in fig: A.4. The next step is to insert a new cylinder in the same way as the previous one and set Operation as Add Frozen and the dimensions in Axis Definition as X component 0 mm, Y component 0 mm, Z component 30 mm and Radius 27.5 mm (fig: A.6 (a )) and if you click on the Generate icon it will appear (fig: A.6 (b)) in the graphics window. Similarly, insert a new cylinder from primitives and set Operation as Add Frozen and the dimensions in Axis Definition as X component 0 mm, Y component 0 mm, Z component 16 mm and Radius 20.35 mm and if you When you click the Generate icon, it will appear in the Graphics View window as shown in Figure: A.8.

Next is to insert a new cylinder from primitives and set Operation as Insert Frozen and the dimensions in Axis Definition as X component 0 mm, Y component 0 mm, Z component 30 mm and Radius 15 mm and if you click on the Generate icon, it appears on the Graphics window as shown in fig: A.9. Go to the Generate icon and click to generate the resulting body, which appears in the Graphics window (fig: A.10). Next step is to insert a Sphere of Primitives (fig: A.12 (a)) then go to the Details window and set Operation as Add Frozen, define Origin X Coordinate 0 mm, Origin Y Coordinate 23 mm, Origin Z Coordinate 8 mm in and Radius 5.5 mm in Origin Definition (fig: A.12 (b)) and it appears in the Graphics window as shown in (fig: A.12 (c)).

Insert a cylinder and set operation as Add Frozen and the dimensions to Origin definition as X-coordinate 0 mm, Y-coordinate 0 mm, Z-coordinate 7.5 mm and Axis definition as X-component 0 mm, Y-component 0 mm, Z component 1 mm and Radius 25.91 mm and then click the Generate icon. Then enter Boolean and set Operation as Subtract and select Target Bodies as Cylinder 5 and Tool Bodies as Cylinder 6 and then Generate. Next is to insert a Sphere of Primitives and then go to the Details window and set Operation as Add Frozen, define Origin X Coordinate 0 mm, Origin Y Coordinate 23 mm,.

Then insert a boolean value and set the operation as subtraction, the target bodies as a ring (Figure: A.17 (a)) and the tool bodies as eight balls (Figure: A.17 (b)). In the next step, insert a new cylinder from the primitives and set the Operation as Add Frozen and the dimensions in the Axis Definition as X component 0 mm, Y component 0 mm, Z component 30 mm and Radius 21.59 mm and when you click on the Generate icon it will appear on the graphical window as shown in the figure: A.20. Then insert the two cylinders from the primitives and set the Operation as Add Frozen and the dimensions in the Axis Definition as X component 0mm, Y component 0mm, Z component.

Then insert another Boolean value and set Operation as Subtraction, Target Bodies as eight balls (fig: A.26 (a)) and Tool Bodies as the ring (fig: A.26 (b)) generated above this step.