Assignment #4
Problem Statement: Develop a mechanical device that lifts a camera up to at least eye level so that it can be used for pipe inspections inside of a nuclear power plant.
Decision Matrix: Creating this decision matrix helped me to pick which design to pursue. I picked criteria that was technical, but not overly specific. The utility was an important aspect within my designs because I wanted what I ended up making to be both usable and necessary.
Weights vary from 1-5 with 1 being the lowest and 5 being the best rating each aspect can achieve.
The clear winner from this matrix was the drone, especially since it offered far more utility than the other design options. The drone is able to achieve far greater rights than the other options. It also scored well in producable since there are many common off the shelf parts that can be used.
Assumptions: There are several assumptions made within the module stages of this design. Some things were assumed such as the max length of the cable. The max force on the wheel was also estimated. All three tether designs utilize the same overall design with some differences in how the spool is wound. For my three different modules, I focused on how the tether would be operated. They all used the same universal one-way bearing and parametric spool, but each module focused on various ways to operate it. These include manual operation, a gear system with a motor, and a highly efficient pully reduction system.
Some outside parts were used for the sake of creating renderings of the modules.
Bearing from McMaster-Carr 60355K505
Stepper Motor 23HS41-1804S
A one-way bearing was designed into the spool to allow for free motion in one direction and then allow for the hand crank and or motor to engage with the spool in the other direction.
One-way bearing pictured below:
Module 1 Hand Crank:
This module focuses on a manual way to wind up the tether. This utilizes a hand crank. An in-depth analysis was considered to come up with the correct sizing. Parametric design techniques were utilized to create equations that could later be easily edited to change things such as the outer diameter of the spool or the crank handle spacing.
FREDPARC Module 1:
Analysis:
Forces, stress, and power were analyzed.
It was found that the design needed to allow for maximum shear stress in the central shaft of 260KSI.
The maximum force that would need to be applied to the crank is 4.8 lb.
The power required to spool up the rope was found to be 1 watt.
The Design (3D models):
Parametric equations:
Strategic aspects of the design were put in equation form so that it could be easily edited later on. These included the outer diameter of the spool, the inner diameter, and width.
Renderings of the Module:
Module 2 Gear Drive:
This module utilizes a gear system to wind up the spool. Some of the same analysis still applies from the previous, but this time more was added. Gear ratios were considered and the required motor torque was estimated. Power equations were updated. Parametric design techniques were utilized to create equations that could later be easily edited to change things such as the outer diameter of the spool, gear pitch, teeth, and more.
FREDPARC Module 2:
Analysis:
As before Forces, Stress, and power were analyzed, but in this case gear ratios and required motor torque were also determined.
It was found that the design needed to allow for maximum shear stress in the central shaft of 260KSI.
The power required to spool up the rope was found to be 147 Watts
The torque required in the motor was found the be 5.33lbin
The Design (3D models):
Parametric Equations
Involute parametric gears were designed to allow for easy changes in the gear ratio. The assembly was constrained in such a way as to allow for the changes in gear sizes, automatically updating the motor mounting position.
Renderings of the Module:
Module 3 Belt & Pulley:
In this module, a belt and pulley system is used to wind up the spool. Some of the same analysis still applies from the previous, but this time more was added. Gear ratios were considered and the required motor torque was estimated. Parametric design techniques were utilized to create equations that could later be easily edited to change things such as the outer diameter of the spool, gear pitch, teeth, and more.
FREDPARC Module 3:
Analysis:
As before, forces, stress, and power were analyzed, but in this case pulley ratios and required motor torque were also determined.
It was found that the design needed to allow for maximum shear stress in the central shaft of 260KSI.
The power required to spool up the rope was found to be 82.9 watts.
The torque required in the motor was found the be 3 lb-in.
The Design (3D models):
Parametric Equations:
The pulley system was designed as a single part file that could be edited with parametric equations. Both gears could be resized as well as the belt length.
Renderings of the Module:
Gantt Chart:
Download here
Lessons learned:
While doing this assignment I learned the importance of good modeling techniques. Without proper constraints being applied changing the parametric equations would result in errors within the design. These errors were all overcome by applying propure constraints to the different sketches.
Time Management:
11-10-2020 10:30 am-12:00 pm Brainstorming and initial decision matrix implementation
11-10-2020 2:00-5:00 am sketches, equations, and writing
11-11-2020 8:00-11:00 am Solidworks design
11-13-2020 1:00-5:00pm design and website implementation.
Comments to Advisees:
Advise to Dylan Appleyard:
Overall it looks good! My one piece of advice would be to add more design parameters. You seem to just have one design parameter per functional requirement.
Advise to Hunter Joyner:
Your assignment is well thought out and shows that a lot of effort was put into it! The finite element analysis is a nice touch. The biggest issue that you should probably fix is I don't see a way to download your SolidWorks files? It appears you don't have them available on your site which is a requirement of the assignment.