Winona State Composite Materials Engineering

Design Project I/Design Project II

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Design Concern Table


A Design Concern is a characteristic of the product that customers would determine as important. How well these concerns are met determine the quality of the product to the consumer. A Requirement is a numerical value that each Design Concern must meet for the product to be successful. A Goal is either a minimum or maximum that is a desireable achievement for each design.

Lightweight: The cooler will mainly be used for camping trips and needs to be carried easily. Minimizing this would allow for convenience in bringing along a self-cooling cooler places. Design 1 was determined to be the lightest weight.

Adequate Volume: Having a 1 square foot of volume was the size that most outdoors people liked to at least have to carry around food and drinks, which was found from the survey. All three designs meet that requirement.

Temperature Reduction: Having a cooler that can cool itself was the goal of this project, with that being said having the cooler reach the coolest temperature possible would be exceptional. The insulation and volume of the cooler design were factors going into achieving a minimal temperature possible. All three designs ended up with the same minimum achievable temperature possible because the same thermoelectric unit was used which ideally would cool all of the coolers to the same temperature.

Insulation: The cooler would ideally reach room temperature very slowly, which would indicate a very good insulation value. The time to reach room temperature from 40°F should be a maximum value. Again the volume of the cooler and the insulation used would be factors of this. Design 1 received the highest value followed by design 3.

Food Safe Materials: Making sure the material was food safe was very important. The material chosen was polypropylene which needed to be acceptable and also had to have at least 2000 ppb which would be acceptable to store food in. The polypropylene met that value in all three designs.

Will Not Degrade when Exposed to Water: Setting the cooler on the ground will most likely be a common scenario, and the ground isn’t dry all of the time. The cooler needed to be able to not degrade when exposed to water from either the ground or spills in or on the cooler. A specimen of polypropylene was put in water for 24 hours and a flexural three point bend test was run on it and compared to the polypropylene specimen that was not soaked in water at all. There was a requirement that the soaked specimen had to retain 90% of strength that the unsoaked specimen contained. The results gave a 91.23% strength for all three designs.

Ergonomics: Having to carry the cooler should not be a struggle for the users, which means that the location of the handle should be a minimum value from the top of the cooler to insure ease of carrying. Design 2 and 3 had similar measurements for the location of the handle compared to the large measurement that design 1 gave.

Ease of Access: The weight of the lid should be such that a minimal amount of force could be used to open it. The factors that went into this was the size of the lid and the depth of the lid, since all three of the lids would contain the same insulation. Design 1 ended up weighing less compared to the other two designs.

Life Span: The cooler would ideally last a long time, so looking at the life span of the cooler material, solar panel, battery, thermoelectric unit and the insulation were all investigated. The battery was found to be the item that would need to be replaced the soonest, which was about after two years of use. This was the same throughout all three coolers.

Affordable/Competitive Cost: The cost of the cooler should be low enough to attract all kinds of customers but large enough to give a profit. Factors that went into determining the price of the cooler was the cost of all the materials (polypropylene, insulation, handles, latches, battery, solar panel, thermoelectric unit). Design 1 was the most affordable cooler with design two close to it.




Last Updated: 4/22/15