Expanding Structure

Level: Elementary School, Middle School, High School

Type of Contest: Team

Composition of Team: 1-5 students per team

(It is strongly encouraged to have four team members.)

Number of Entries: One entry per school

Next Generation Science Standards: ES-ETS1-2, ES-ETS1-3; MS-ETS1-1, MS-ETS1-2, MS-ETS1-3, MS-ETS1-4; HS-ETS1-2, HS-ETS1-3.

Overview

Engineers solve many kinds of problems. Often they are given very specific design criteria and asked to develop the optimal solution. Sometimes they can only use certain materials. Sometimes their devices must only use a certain amount of energy. Sometimes their structures must be able to hold up a certain amount of weight.

Regardless of the project, engineers are almost always given specifications related to size. For example, the final product might need to fit inside a specific-sized container. Engineers have to think about how to fit all the components required for a project into a small space. Think about all the components that fit inside your laptop. Other times, the final product must not be too small; it must be at least a specific size. For instance, an engineer designing a hang glider must make the wing a minimum size to keep the rider in the air. The seat of a car must be a minimum size to allow a person to fit. A bridge must be a specific length to cross the valley below.

And sometimes, engineers are given a really tough challenge: They must design something that is both big and small. These engineers need to think of ways to fit large, strong structures into tiny containers. Think about solar panels on some spacecraft. The panels must fit into tiny containers when launched from earth, but to harness enough energy to power the spacecraft, they need to be huge when deployed in space. And the panels need to be strong so they don’t break when deployed. It isn’t easy to repair things in space. On top of that, the panels need to be light. The lighter they are, the less energy needed to launch them into space. In other words, engineers are looking for an efficient design. Lightsail 2 is another example of an expanding structure in space.

You can check out a different type of expanding structure project here. The video shows a sonobuoy being dropped into the ocean from an airplane. Once it hits the water, it expands to create a huge structure that holds microphones. When deployed, the sonobuoy can be used to pick up all kinds of sounds in the ocean like whales, dolphins, and boats.

Engineers at the Johns Hopkins University Applied Physics Laboratory are working on challenges similar to the sonobuoy project. These projects require large, strong structures that fit into small containers. The engineers are designing ways for the structures to expand and still be strong. Sometimes, the structure expands automatically; other times it requires assembly of the components.

NOTE ABOUT 2020-21 Competitions

Due to the impacts of COVID-19, there will be no in-person MESA competitions for the 2020-21 MESA season. Instead, all projects will be submitted electronically to virtual competitions. Judges will score projects remotely.

For the County Competition, all files must be submitted no later than 11:59 pm on the due date specified by the MESA County Coordinator.

The team that wins the County Competition will progress to the 2021 Maryland MESA State Competition. Like the County Competition, all projects will be submitted electronically no later than 11:59 pm on the specified due date.

oVERvIEW

In this MESA challenge, students will use the engineering design process to design and build an expanding structure. The main goal of the project is to build the most efficient structure possible. That is, the final design should be as light as possible and support as much weight as possible while meeting all design requirements. The structure will be made of components that fit entirely inside a transport container of a specified size. The structure will have the capability to be deployed/assembled to span a greater distance than the length of the transport container. When testing the structure, the team will remove the components of their structure from the transport container, assemble the structure, and demonstrate the strength of the deployed structure. For the 2020-21 MESA Competition, teams will submit a video-recorded presentation about their design process and their final solution.

gENERAL dESIGN rEQUIREMENTS AND cONSTRAINTS

Teams must follow these general design requirements:

Only the materials included in the Maryland MESA Expanding Structures Kit may be used to build the structure.
All components of the structure must fit inside the transport container at the same time. No part can protrude from the transport container.
The structure must be able to be deployed/assembled quickly. The structure must be designed in a way that it can be removed from the transport container and assembled on the testing apparatus in less than 4 minutes.
When deployed/assembled, the structure must span a specified distance.
There are no specific minimum or maximum length (other than the distance the structure must span), width, or height requirements for the assembled structure. However, the assembled structure must be able to support a loading plate on the top of the structure in the center of the span. The structure does not necessarily have to be the same width as the loading plate. It may be wider or narrower than the plate if the team chooses.
The total mass of the structure must not exceed a specific limit.

Critical Design Parameters

Transport Container: Before being deployed/assembled, all parts of the structure must fit inside the provided transport container at the same time. The transport container is an 10”-long tube with an inside diameter of 4”.

Span: When deployed/assembled, the structure must span a distance of 12” (± 1/16”). During testing, the structure will be placed on a testing apparatus. The apparatus will consist of two 3”x3” platforms 12” (± 1/16”) apart (see the diagram in the Appendix). The structure may rest completely on top of the testing apparatus, or the team may decide to allow the structure to extend below the top of the testing apparatus. The structure may extend no more than 23/32” below the top of the testing structure.

Total Mass of Structure: The combined mass of all components of the structure may not exceed 80 grams.

Loading Plate Support: The structure must be designed and constructed so that a 2.5” x 2.5” loading plate can rest on top of the structure in the center of the span. A 6”-long 1/4” eyebolt will be inserted through a hole in the center of the loading plate and secured with a nut (see the diagram in the Appendix). The structure must be designed so that the loading plate is horizontal when placed on the structure and the eyebolt hangs vertically. A bucket will be hung from an S-hook attached to the eyebolt.

Materials

The Maryland MESA Expanding Structure Kit includes starter materials that may be used to construct the structure. Teams may choose to use all the materials in the kit. Teams are not required to use all the materials included in the kit.

Wood—Basswood is the only type of wood that may be used. All pieces of wood used must have originated as pieces measuring 1/8” x 1/8” in cross-section (Stock #: 970022 at Kelvin.com). In other words, no pieces with a cross-section larger or smaller than 1/8” x 1/8” may be used.

Adhesive—Sobo Craft Glue is the only adhesive that may be used. This glue is available at many local and online retailers.

String—Only the string (i.e., dental floss) provided in the Maryland MESA Expanding Structure Kit may be used.

Rubber Bands—Rubber bands may be used to construct or assemble the structure. Teams may use the rubber bands provided in the Maryland MESA Expanding Structure Kit or may provide their own. There are no restrictions on the size or number of rubber bands used.

MESA Stickiez—Any or all of the connectors (aka MESA Stickiez) provided in the MESA Expanding Structure Kit may be used. The Stickiez are lettered A–J (see the diagram in the Appendix). The team may use a maximum of eight (Elementary) or four (Secondary) of each type of Stickiez. For example, the team can use up to eight of part “A,” four of part “B,” four of part “C,” and so on.

The team will need to supply a scale and test weights, which are not included in the kit. Inexpensive test weights can be made with common household materials.

Construction Parameters

Only the materials listed may be used.
The materials provided in the Maryland MESA Expanding Structures Kit may be notched, cut, reshaped, and/or sanded.
Wood pieces of the structure may be laminated. In other words, strips of 1/8” x 1/8” wood can be glued together to make thicker beams.
The structure must not be painted. However, marks may be added to pieces to help with assembly.
Care should be taken when gluing to make sure excess glue does not cover a significant portion of the structure. Glue should be used to adhere pieces together and should not be used to cover a significant portion of the structure. Judges may disqualify an entry if the structure appears to have glue that covers a significant portion of the structure.

Testing the Structure

During testing, teams will follow the procedure below:

The team will have 3 minutes to remove all parts of their structure from the transport tube, assemble the structure on the testing apparatus, place the loading plate and eyebolt (with attached S-hook) onto the structure, and hang a bucket from the eyebolt. The structure must be assembled without the use of tools.

Note: The testing plate and eyebolt do not need to be placed inside the transport tube.

The team must place the loading plate on the center top of the structure. The loading plate must be horizontal when it rests on top of the structure.
The team must attach a 6”-long 1/4” eyebolt (with attached S-hook) to the loading plate. The structure must allow space to receive the bolt for loading/testing.
The team must attach a bucket to the eyebolt. A loop of string will be attached to the handle of the bucket.
Team members will add weight to the bucket hanging from the structure. Competitors may not hold the bucket up with their hands and may only make brief physical contact with the bucket while loading.

Weight will be added until the structure fails or until a load mass of 15 kg (15,000 g) has been reached. Structural failure is defined as:

a. The structure breaks and no longer supports the loading plate and weight.

b. The structure deflects (that is, sags or bends) 23/32” below the top of the testing apparatus.

Note: The overhang on the wooden testing apparatus is 23/32” so this can be used as a visual indicator.

c. The structure falls over. If a structure falls over, the structure will have failed regardless of deflection.

Note about weights for testing: There are many ways teams can make inexpensive weights to use when testing their structure. For example, sandwich bags can be filled with sand, salt, or rice. Other household objects like small water bottles, aquarium gravel, or books could be used. It is beneficial to have a wide range of test weights (e.g., 10g, 50g, 100g, etc.) and to have multiple weights at each increments (e.g., many 10g weights, many 50g weights, etc.).

Structures failing above 15,000 g will be considered to have held 15,000 g for the efficiency calculation.
The recorded mass held will be the last mass held before the structure fails. The mass at which the structure fails will not be recorded as the mass held.
Eye protection must be worn while loading/testing the structure.

Calculating Efficiency

Efficiency of the structure will be calculated using the following formula:

Efficiency = Mass held by structure ÷ Mass of structure

The following table shows example efficiency calculations for two teams:

Team A Team B

Maximum Load (g) 7,000 g 4,000 g

Structure Mass (g) 13 g 10 g

Efficiency = (g/g) 7,000 g ÷ 13 g = 538.46 4000 g ÷ 10 g = 400.00

Team A’s structure has a higher efficiency than Team B’s structure

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