Digital twin by DEM for ball bearing operating under EHD conditions

Prediction of Thermal Deformation for a Ball Screw System Under Composite Operating Conditions

The position error of a feed drive system is mostly caused by thermal deformation of a ball screw shaft. A high-speed ball screw system can generate massive heat with greater thermal expansion produced, and consequently have a negative effect on the positioning accuracy. In this study, we applied the computational approach using the finite element method (FEM) to simulate the thermal expansion ...

Point processes for bearing fault detection under non-stationary operating conditions

Bearing faults represent the most frequent mechanical faults in rotational machines. They are characterized by repetitive impacts between the rolling elements and the damaged surface. The time intervals between two impacts are directly related with the type and location of the surface fault. These time intervals can be elegantly analyzed within the framework of renewal point processes. With suc...

Performance of Photovoltaics Under Actual Operating Conditions

Ball-Bearing Motor

The discovery/invention of the ball-bearing motor is attributed to Milroy [1]. It has been discussed several times, with conflicting explanations [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]. This solution is a much simplified version of that given in [7]. Because the motor is weak, it is helpful to reduce friction on the axle by connecting the high-current lead to the outer races of the ba...

B Ball Bearing ▶ Bearing Bar Extrusion

Introduction Bar extrusion is a process in which a block of metal (billet) is forced to flow by compression through a tool (die) opening of a smaller crosssectional area than that of the original billet. There are two basic types of bar extrusion: direct and indirect. The most important and common method used is the direct extrusion (Lange 1988). Figure 1 shows the principle of direct bar extru...