Our customer came to us with an engineering drawing of a large 20 x 20 x 8ft rectangular pressure vessel with strict review requirements. This structure is part of an emissions treatment system handling noxious, pressurized gasses so it was important that they see no failures in service. The structure was modeled using surfaces in FEMAP and then meshed with plate elements in quarter symmetry. The first pass showed the structure did not meet the ASME Section VIII, Division 2 stress classification requirements. Design iterations were performed to find a solution that would work within their manufacturing limitations. With these modifications in place, linear static analysis showed that the structure would pass. As a follow-up, the customer wanted assurance that the pressure vessel would handle the operating pressure without failure. Running the model with nonlinear material properties and inspecting the plastic strain allowed us to say with confidence that the structure was safe.
The type of work they do means that they require a "slip-clutch" which engages when the drill bit jams and sufficient torque is put onto the "slip-clutch" mechanism. This stops the violent wrenching motion that a drill without a clutch would cause when stopped suddenly from full speed, protecting the drill from damage. The slip-clutch also protects the operator, but does not always prevent injury. Some manufacturers have introduced additional technology to protect the operator. Hilti has a technology called "ATC" or "Active Torque Control"  which works by disengaging the drive from the motor when the tool body begins to rotate excessively through the action of a secondary magnetic clutch in addition to the standard slip-clutch. DeWALT has a related system called "CTC" or "Complete Torque Control"  which utilizes a two-position slip-clutch so that the operator can select the lower torque setting for greater safety.