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=== Costs ===
== Costs ==
Use [[Help:Table_examples#Cost_Table]].
Use [[Help:Table_examples#Cost_Table]].
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Revision as of 00:29, 24 April 2017

Template:ENGR215inprogress

Final Shake Table design without the cart.

Abstract

A Shake Table was designed and constructed to imitate earthquake magnitudes to help students at Zane Middle School to better understand seismic activity and allow them to test their own building structures.

Background

Zane Middle School is a STEAM ( Science, Technology, Engineering, Arts, and Math ) school that believes hands on learning is very important for student success. For several years Engineering 215 students at Humboldt State University have teamed up with Zane's faculty to help them achieve this goal. In Spring 2017, our team was challenged with the construction of a Shake Table that demonstrates shaking of an earthquake. Our Shake Table design specifically allows 7th grade students to learn about the seismic activity in Earth’s crust during an earthquake while also providing a way for them to be creative and test their own building designs.


Problem statement (Objective) and criteria

The objective of our design was to make the most realistic shake table design possible, and satisfy the needs of our client, Zane Middle School. Our client expressed their desire to illustrate the effects of liquefaction of earth during an earthquake and how the earth undergoes a wave motion at these times. Most standard shake tables don’t express this motion so this was one of our challenges. Aside from that, our primary concern was to ensure the device was safe as children would be interacting with it in close proximity.

Below is a table of our criteria and weighted values of importance that our team and client agreed upon:

Criteria Constraint Weight
Safety Safe to be used by teacher as well as the students. Also safe for any bystanders. 10
Sturdiness Table stays stable during use and shaking. 9
Cost Less than or equal to $300 ($100 from Zane Middle School, $50 from each group member) 9
Shake Levels At least 3 different shake levels. 8
Portability Able to move or be store (portable or foldable). Can be brought to other classrooms easily. 8
Ease of Use Able to be used by students as well as the teacher without confusion or damage. 8
Educational Value Able to teach the students about the effects of earthquakes just by using it. 7
Durability Sustain use for many years. 7
Consistency Same shake every time it it used. 6
Aesthetics Aesthetically pleasing. 5

Description of final project

The name of the final design of the shake table is “ .” This design meets the criteria and uses the Flex Board design combined with the Drill Sergeant’s power mechanism to achieve an efficient shake level that safely tests structures built by the students at Zane Middle School. Most of the materials were obtained from local stores, or donated.

This shake table uses a drill to turn an axle, which translates movement along a metal shaft in order to shake the table top. The top of the table is composed of seven wooden slats, each 21 inches long, three inches wide, that are held together using plastic tubing and epoxy with small compression springs in between each slat as shown in figure 1. The structures that are built by the students will be held to the top of the shake table using straps that are connected to a few of the slats. The top of the table is supported by a total of eight compression springs that are connected to five of the seven wooden slats, three of the slats will have two springs connected to them, but two of the slats will only have one spring, as shown in figure 2. The compression spring that support the tabletop are held in place by a combination of epoxy, setting the end of the spring into the board one-quarter inch, and also compressing the springs one-quarter inch using a wire clamped with aluminum ferrules as shown in figure 2.

The shake table is mounted onto a metal cart that is almost four feet tall, two feet long, and three feet wide, as shown in figure 3. The cart rolls on two regular and two locking casters to prevent movement during testing, but also provides an outlet to power the corded drill that shakes the table top. The cart is big enough to allow the students to watch the structures be tested, and has shelves beneath the shake table to allow for more storage space.


Costs

Use Help:Table_examples#Cost_Table.

Quantity Material Source Cost ($) Total ($)
2 1”x4”x8” Wood Boards Ace Hardware 8.99 17.98
8ft. Vinyl Tubing Ace Hardware .23 1.84
1 Red Spray paint Ace Hardware 4.99 4.99
6 Compression Springs Ace Hardware, Arcata 3.29 19.74
2 Compression Springs Ace Hardware, Sunny Brae 3.49 6.98
1 Steel Bar The Mill Yard 3.49 3.49
12 Aluminum Ferrules Ace Hardware, Arcata .80 9.60
2 Aluminum Ferrules Ace Hardware, Sunny Brae .99 1.98
12 Mini Springs Ace Hardware, Eureka .75 9.00
1 Epoxy Ace Hardware, Eureka 4.99 4.99
1 Axle Hub Arcata Scrap and Salvage 5.00 5.00
1 Drill Pierson Building Center 50.00 50.00
1 Base Board The Mill Yard Donated 0.00
6ft Braided Wire Cable Marty’s Shop Donated 0.00
1 Cart Zane Middle School Donated 0.00
Collin and Marty’s Help: Drilling, Sawing Marty’s Shop Priceless 0.00
12 Wood Screws Marty’s Shop Donated 0.00
1 Bolt Marty’s Shop Donated 0.00
4 Spokes Arcata Scrap and Salvage Donated 0.00
2 Metal Corner Braces Marty’s Shop Donated 0.00
2 Aluminum Ferrules Marty’s Shop Donated 0.00
Total Cost $135.59

Testing Results

When testing the shake table for the first time, it showed that the flex board method worked and created the wave motion that was originally theorized but there were still a few issues that needed to be mended. These issues included the vinyl tubing coming out of the end wood slats and the screw connecting the steel bar to the cam system jamming and stopping the movement. These minor complications were remedied by threading the left over spokes from the axle hub through the vinyl tubing to hold the it place. The jamming screw was fixed by adding thread lock to the end of the screw to keep it from over-tightening on the steel bar.

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