The Analysis Of My Project "Design & Development Of Longboard Test Apparatus"
INTRODUCTION
The title of the project is “Design and development of Longboard Test Apparatus” where I have explained my contribution in it through this episode. I executed this project as a requirement for my Mechanical Engineering Undergraduate Degree, in my final semester at Sligo Institute of Technology, located in Sligo, Ireland. I was able to develop this project with the constant guidance and support of my project supervisor, Prof Micheal Moffit. Having started the project in 2010, I was able to successfully complete it in 2011.
Nature of the project
As per any commercially manufactured product on a large scale, it becomes imperative to conduct an intensive test of the product and simulate it to every possible set of conditions. This enables the manufacturers to ensure quality, improve designs and provide warranties based on results. Hence, there is seen the demand for designing an apparatus to precisely simulate the riding conditions of the customers, and we are able to achieve this by using the longboard test apparatus.
The Longboard Test Apparatus uses a four-bar, frame, and two spinning disks and generates a device that will until failure, fatigues and yields a complete longboard skateboards. The loads are designed to simulate every road conditions including rocks, sidewalk cracks, etc. and the distribution the weight of a 300 lb. rider on the longboard. This tested longboard is equivalent to a longboard of the average distance, speed, and wear for 2 years.
I developed this project during the final year of my undergraduate degree at the Sligo Institute of Technology. Apart from being recognized as Ireland’s No 1 destination for Digital Education, IT Sligo has also produced several internationally acclaimed ground-breaking research in Science and Archaeology. To undergo a review of all the literature materials associated with the project and all the project attempting to implement the same mechanisms. To devise an effective design to simulate the prolonged use of the longboard. To cautiously decide on the components of the apparatus and design a way of implementing them together. To derive a mechanism of manufacture or the process of assembly of the apparatus. To devise a smart design verification plan to validate the design. To formulate a scheme for enforcing and applying mechanisms for maintenance and safety consideration.
Personal Engineering Activities
In order to enhance my understanding and vision of the project, I looked over a lot of published articles and journals relevant to the topic. I researched extensively on previous projects with the similar scope and objectives. I revised my theoretical knowledge of numerous techniques of stress/truss analysis, fabrications, drafting and solid modelling. I furnished my skillset with new practices of finite element analysis, hydraulics and loading. I discussed any potential issues or doubts with regard to my project with my project supervisor and other academic faculties. I availed the services of the library to gain perspective and idea on the matter.
After review of the literature, I went through several brainstorming session to develop a finalized design after analyzing with QFD. For implementing the disk road simulator, I chose plywood of 8’ x 4’ sheet and cut in half widthwise leaving two 4’x4’ squares. I used a 1 ½”galvanized plumbing pipe for the bushing and placed it in the centre of the base. Then I screwed 8 casters into the disk and placed them in such way that the weight was distributed evenly across the disk. For the assembly of the prototype, I placed the top disk on the base. I mounted the front bicycle wheel in a bicycle lock rack and placing the back wheel on the disk achieve a speed of 15mph to drive the disk.
The tests run included placing the board in various positions on the disk. These included: four wheels on the disk, Front trucks only with two wheels in contact, and front trucks only with only one wheel in contact and the other off the edge of the disk. For freeboard, I placed the front trucks in a way that a toe side stop or a heel side stop could be simulated. Also, I created the system to have the caster on the edge of the disk and rolling onto the already spinning disk and then turning off. This would create a carving motion and caster load if two disks were used.
For the next phase, I underwent a thorough analysis and design decision of the components of the testing apparatus. To simulate a forward motion parallel to the board, I chose a road simulator design to pursue is the two disk idea. As I knew from prior experience, the frame needed to be sturdy enough to contain the two disks and the oscillating weight shifting back and forth. For the rollers, I used straight wheels to support the disks. I used the four-bar linkage to actuate all carving/turning for both board types as it allows, for a motor to rotate freely and, through calculations, a rocker arm was tuned to oscillate between two desired angles. I designed the Weight Assembly to simulate a 300lb rider and acted as the interface between the four-bar linkage and longboard. I implemented the Island Assembly for the purpose of the island assembly to allow the fatigue tester.
The next step required the assembly of all the components chosen in the phase prior. I designed the lower frame to support the upper frame, weight assembly, two maple disks, four-bar mechanism/drivetrain, and disk stabilizers. I developed the disk stabilizer solely out of welded 1/8” thick steel sheeting. I slid the upper frame onto the lower frame, which allowed the fatigue tester to have more module properties and is easier for storage at the factory. I attached the island to the centre of the lower frame and in between the minimum distance of the two spinning disks.
I included adjustable loading weights and the securing of the board of the weight assembly. I purchased a Bell Cyclometer bicycle computer to monitor the large 3.5’ disk’s speed. Four-Bar uses the point between the rocker and the coupler push a moment arm. The four-bar mount that I had chosen was integrated into the upper frame. The drive train consisted of our motor, a toothed belt, two gears, a drive shaft, and two rubber wheels, including housing for the driveshaft. I made the disks out of laminated maple plies with symmetric screwing.
As needed for any successful implementation of the project I verified the apparatus is in its intended working condition. I devised a Design Validation Plan and Report (DVPR) which will test all aspects of the customer requirements. Each specification has a complimentary test which it passed to the satisfaction of defined acceptance criteria. When testing took place, each specification was assessed to see if it passed the acceptance criteria and the date and any additional notes were recorded. While developing this plan, I ensured that all aspects of the beginning customer requirements were tested to their acceptable level.
For ensuring the feasibility of the product, the maintenance and safety parameters needed to be addressed. I implied that by ensuring to keep maintenance costs low and convenient. I fabricated most of the parts in-house such that it was easy to remanufacture broken parts. I had designed the caster wheels to be supported with bearings and mounted with the caster axels and speed washers. I also connected the bearings and the linkages of the four-bar together, along with 8 mm shafts.
The frequency of machine maintenance was driven down because of the carefully calculated safety factors with which each component was I had chosen. The disk stabilizers were designed to be removed so that the disks were pulled out. I designed the frame as two pieces, and I did not integrate the drive train into the frame for maximum portability. For enforcing safety, I placed a safety enclosure on the front and top of the frame, made out of polycarbonate Lexan glass. I introduced a kill switch into the machine to shut off power to the motors when the board breaks.
During the Implementation phase, I realized a major roadblock, I had initially chosen on the suggestion of our project supervisor, a conveyor belt road for the road simulator, as it was the most practical in being able to simulate the road type. After I conducted research on the market, it was clear the conveyor belt road was not going to be a possibility. The main driving factor was the price of the conveyor belt. Further, a custom belt would be required that could be durable enough to handle our desired load would cost close to three times the overall project budget. On having spoken to my teammates, I decided to pursue the spinning disk idea to simulate the road. I
designed the disk road simulator using a plywood 8’ x 4’ sheet and cut in half leaving two 4’x4’ squares. I used a 1 ½”galvanized plumbing pipe for the bushing and placed it in the centre of the base. Then I screwed 8 casters into the disk. For the assembly, I placed the top disk on the base. I mounted the front bicycle wheel in a bicycle lock rack and placing the back wheel on the disk achieved a speed of 15mph to drive the disk. This greatly helped us achieve the desired simulation and met our budget boundaries.During the testing of the four-bar, I discovered that the carving motion of the board was wrong. Instead of dragging the back edge wheels during a turn, the front wheels were being pushed towards the direction of the turn.
Furthermore, the caster wheel was following the convex path of the rocker linkage. This was an issue threatening the credibility of our project as in order to properly simulate how an actual rider would carve on board by having the back edge wheels dragged behind the direction of the turn; the caster would have to follow a concave path. After in-depth analysis, I proposed two solutions one to flip the four-bar upside-down or use the point between the rocker and the coupler push a moment arm. On discussion the latter solution was chosen as the board could be tested with only a little adjustment. After this update, the caster was able to follow a concave path.
In order to build the weight assembly which included the adjustable loading weights and the securing of the board to the weight and fatigue system. I attached the top of them to the upper frame via a telescoping rod which further attaches to a ball socket joint on top of the upper frame. The weights were 200lbs of 8*25lb plate weights. The telescoping rod allowed the rod to contract and extend so that the board was able to stay in contact with the wooden disks. If the rod was fixed, there was a chance the board could be lifted off the tester if not properly tuned.
I was required to coordinate our actions and take all major design decisions, as the team leader. I communicated with my team members and faculties constantly to review our progress and issues. I issued tasks among my team members as per their capability and experience. I always encouraged the generation of new ideas and designs for my members. I deployed Gantt charts to ensure our productivity and schedule dedication. I conducted meetings on weekly and submitted the minutes of the meeting (MoM) to my supervisor.
I always attempted to respect and abide by any rules and guiding regulations imposed by Sligo Institute of Technology. I believed to have conducted myself with high standards of ethics and professional behaviour. I always observed any decision from both professional and ethical point of view. I followed ISO 10721-2 for metal fabrication. I also indicated any reference to any material for the internet.
Summary
In the end, I along with my teammates were successfully able to develop an apparatus to test longboards, well within the budget and time constraints. This project gave me a chance to reinforce my learning and apply my theoretical knowledge into practical use. I also learned the fundamentals of project management and acting as the team leader, has helped me in team management and develop my leadership skills. I exposed myself to the longboard technology and mechanics, disk simulator structures, etc.
