Our project is tailored to help a 2 year old who is growing very quickly. The child is about the size of a 4 year old, and still has developmental needs at her current age. Our goal is to help with one of those needs while she is at the dining table. We were tasked with designing a specialized highchair that will help with her development needs no matter where the family would go. This chair will help the child, keeping her comfortable while she grows up, and help the family with providing care for her.
The chair needs to assist the child for at least three to five years during her development as a growing child. The chair must be a safe and inviting for the child, as well as practical for the family. It must be easy to use, clean, and move. Making it portable so the family could take it to public places like restaurants was also requested. All these things are important, as it will help the family use the chair while the child still needs it.
While the chair needs its practical components, there are also some stimulus things we must focus on retaining for the child, as we are building an environment to help her feel comfortable while she eats. One of the simpler, yet equally important requests was a cupholder. We must focus on designing a seat and backing that are both sturdy and ergonomic for maximum support during use.
For portability, we are still assessing ways we could make the chair fold into a smaller shape. With our time, we are looking for a practical working solution. Our current ideal goal is to make sure that the chair operates smoothly, but the structural integrity of the chair is our first priority.
For our research, we referenced the current highchair the family was using to see what the child may desire in a chair. This gave us a rough idea of what the child would enjoy in her highchair. We also referenced other folding chairs, to see how we could design a mechanism to help the chair fold for portability.
Images in order:
1. The current chair the family is using.
2. Some current market designs look similar to this.
3. Folding chair we looked at for mechanism inspiration.
4. Foam seat inspiration.
For our first Concept Design, we brainstormed on the idea of the chair having adjustable height, arm width, and adjustable tray position. This would allow for the chair to be adjusted to any height, as well as give the seat any size that would be needed. The height latching mechanism for chair designs 1 and 2 are the same. (click image to see full image)
Concept Design 2 builds off of Concept Design 1. The sides are eliminated in favor of only having the chair backing. This simplifies our design in favor of making the seat more comfortable to sit in. The tray is attached to one arm and has a leg divider that can be removed as needed. The tray could be slid towards or away from the chair backing, as well as left or right on the bar it sits on. Since adjustable height was not needed, we opted to remove it in favor of a portable design. A sliding mechanism was designed so the chair could be folded into a compact form, ideal for sitting in the back of a car. The gif animation provided is how we imagine the sliding mechanism would function. (click images to see full images and gif animation)
Concept Design 3 takes our second concept design and simplifies the design a lot more. Getting rid of weight and making it easier to adjust. The chair has a simpler mechanism to support it, simply being two legs that are free to move as needed. The tray will have a selection of slide positions to choose from. The frame holding the seat and latching mechanism will be made of aluminum, while the frame of the highchair will be made of a strong wood like poplar. The wood will be sanded and stained accordingly.
Our selected design will be concept design number 3. This design is the most simple and reliable. This will ensure longevity for the family as the child grows. It is also the most compact design we have discussed thus far. None of the designs were particularly more difficult to clean than the others. This removed it as a component we needed to worry about for our final design. This design will also be the most cost effective for the support it can provide. With our limited time frame, this design is the best choice. Not only can we make it functional, but smooth and user friendly. This is a huge priority for the family, and the cushioned seat and specially designed tray should help make the child feel at home.
The chair will be made of a strong wood (like poplar or oak). This will provide something that is not only strong, but lightweight for transportation. The seat frame will be made from aluminum, allowing us to make it small and able to withstand the weight it may face reliably. There will be plastic/rubber feet at the bottom of the chair. These will probably be 3D printed with a plastic like TPU. These will prevent the chair legs from scuffing whatever floor it may be on, as well as adding extra grip so the chair doesn’t slide.
The legs will be made to stand in a triangle formation, giving us a strong truss-like support to hold the weight of the user. The aluminum was chosen to withstand any stresses that the user will put on the seat. This also will allow for a smooth slide when mounting the seat in the highchair frame.
A weather resistant fabric was chosen to make the seat comfortable and easy to clean. The wood will also be sanded and stained, to ensure that it is nice to the touch and stain resistant. All of this should allow for the chair to be stain resistant for any possible spills that could happen. The tray will also be made of a food safe plastic.
The latch housing is expected to experience significant loading, so it must be designed to withstand that force. We chose aluminum alloy 6061 for its excellent strength-to-weight ratio and durability. In our analysis, the sides and bottom surfaces that are connected to the chair leg were defined as fixed supports, while a 250 lb (1112 N) load was applied to the surface attached to the seat. The resulting maximum stress was 17.52 MPa, which is well below the yield strength of 6061 aluminum (310 MPa). The maximum displacement at the farthest point was only 0.00234 mm, an extremely small value. Overall, the latch housing is more than capable of safely supporting a 250 lb (1112 N) person applying their full weight directly on it.
