**7. Shovel stress modeling and analysis**

The steel used for cable shovel dippers and teeth has high strength properties. The yield strength is the most important strength property, as the shovel experiences high levels of stress loading. Limited data is available for shovel components [21]. One research reported csag40.21-350WT steel used for shovel boom [21]. This steel has high yield strength of 320 MPa [21, 22]. It is assumed in this study that the same steel is used for the dipper and the shovel boom, and their properties are given in **Table 4**. The angular rotation and extension of the dipper arm, external digging forces, and dynamic material weight forces from the dynamic simulated model are used as inputs for the virtual prototype. The shovel stress analysis is performed in ANSYS Workbench-R15.0 [30]. First, a rigid-body analysis is performed to ensure that the dipper follows the given trajectory for the given angular rotation, crowd-arm extension, and external forces. Afterward, a transient analysis is performed for the dipper and teeth stress analysis in ANSYS Workbench R15. For this analysis, the dipper-teeth assembly and crowd arm are converted into flexible bodies, allowing ANSYS to compute stresses on the dipper components. All force functions are the same as that used for the rigid-body analysis. The joint functions are defined for the desired trajectory generation. The flexible dipper bodies are meshed appropriately, using sweepable bodies and controlled meshing. The simulations are performed for a 3 s interval. The simulation is run in two steps with multiple sub-steps for better convergence.


**Table 4.** Properties of steel for dipper and teeth.

Stress loading (von Mises) is computed for the dipper-teeth assembly, dipper bottom plate, dipper side wall, and teeth. **Figure 7** shows the representative stress profile. The stresses on the dipper-teeth assembly vary with time. The maximum stress values vary from 151 MPa to 282 MPa. These stress values are higher than the lower limits of yield strengths for low, medium, and high carbon steel (**Table 5**). Permanent damage to the dipper components is possible, if the steel used has lower yield strength. The stress contour maps are used to identify the high and lower stress regions for fatigue fracture modeling and analysis.

Mechanics of Electric Rope Shovel Performance and Reliability in Formation Excavation http://dx.doi.org/10.5772/65333 123

**Figure 7.** Equivalent stress (von Mises) profile of dipper.


**Table 5.** Yield strengths of steel [23].

**7. Shovel stress modeling and analysis**

better convergence.

122 Lagrangian Mechanics

**Table 4.** Properties of steel for dipper and teeth.

The steel used for cable shovel dippers and teeth has high strength properties. The yield strength is the most important strength property, as the shovel experiences high levels of stress loading. Limited data is available for shovel components [21]. One research reported csag40.21-350WT steel used for shovel boom [21]. This steel has high yield strength of 320 MPa [21, 22]. It is assumed in this study that the same steel is used for the dipper and the shovel boom, and their properties are given in **Table 4**. The angular rotation and extension of the dipper arm, external digging forces, and dynamic material weight forces from the dynamic simulated model are used as inputs for the virtual prototype. The shovel stress analysis is performed in ANSYS Workbench-R15.0 [30]. First, a rigid-body analysis is performed to ensure that the dipper follows the given trajectory for the given angular rotation, crowd-arm extension, and external forces. Afterward, a transient analysis is performed for the dipper and teeth stress analysis in ANSYS Workbench R15. For this analysis, the dipper-teeth assembly and crowd arm are converted into flexible bodies, allowing ANSYS to compute stresses on the dipper components. All force functions are the same as that used for the rigid-body analysis. The joint functions are defined for the desired trajectory generation. The flexible dipper bodies are meshed appropriately, using sweepable bodies and controlled meshing. The simulations are performed for a 3 s interval. The simulation is run in two steps with multiple sub-steps for

**Property Value Unit** Density 7900 kg/m3

Young's modulus 2.3E+11 Pa

Tensile yield strength 3.2E+08 Pa

Compressive yield strength 3E+08 Pa

Tensile ultimate strength 4.6E+08 Pa

the high and lower stress regions for fatigue fracture modeling and analysis.

Stress loading (von Mises) is computed for the dipper-teeth assembly, dipper bottom plate, dipper side wall, and teeth. **Figure 7** shows the representative stress profile. The stresses on the dipper-teeth assembly vary with time. The maximum stress values vary from 151 MPa to 282 MPa. These stress values are higher than the lower limits of yield strengths for low, medium, and high carbon steel (**Table 5**). Permanent damage to the dipper components is possible, if the steel used has lower yield strength. The stress contour maps are used to identify

Poisson's ratio 0.3
