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Group 3: Swinging Chair


The goal of this project is to allow the parents to have a therapy chair/swing for their child at their house. The support system and safety of this chair/swing is the parents biggest concern. The chair will have to be mounted on a sturdy frame that can be moved along with straps to secure the child and removable support pieces for the child.

(Left to right) Anna Smith, Tyler Gardner, Nicholas Baker, James York

Problem Statement

The parents are working closely with their therapist to copy a therapeutic swing used to keep the child calm. This swing is a non-motorized swing mounted on the ceiling in the therapist office. They’ve asked our group to recreate this swing for their house, but to include a detachable chair that straps the child in, and is to be removed for parents to join the child on the swing. This swing/frame will need to be mobile so the parents can move and transport the swing as if it were another piece of furniture within the house.

Design Specifications

Parents wants:

  • Motorized with linear and circular motion
  • Ability to swap between motorized and manual movement

Parents needs:

  • Manual swinging chair
  • Harness and support to keep the child portioned upright
  • Frame that can fit comfortably within their house

Background Research

A platform swing, similar to what is shown, is the idea of what the family and therapist are wanting/recommending. Mostly because of the versatility. They are wanting the “blank” slat so that different support pieces can be added and removed depending on what the child needs at that time. These support pieces will range from a simple wedge/incline to something such as the full body support chair shown below.

Most of our research will be focused on the frame/support system for the swing.

Concept Design 1

One of the designs for the swings frame is a basic A-frame design as shown below. The first frame shown is rated to hold up to 440lbs. One downside to this design, is all of the weight of the swing will be at the weakest point, center of the horizontal bar, on the frame. This particular frame was designed to have 2 ropes holding the swing versus the one we will be using. Also, this will have a large footprint.

Concept Design 2

Another frame design that we looked at is the C-frame design shown below. These frames come in different sizes and weight ratings. An advantage of this frame design is the small footprint that it will have. One of the downsides is it might not be stable enough for the circular motion that the parents want to be able to swing the child.

Concept Design 3

The last frame design that we are looking at is a teepee style frame such as the ones shown below. The bent leg frames seem to hold less weight, but proved more room for the swing to move. The straight leg design is stronger, but it is also taller. Since this will be inside a house, we have to consider standard ceiling height. The teepee style does have a smaller footprint than the A-frame, but bigger than the C-frame design.

Selected Concept Design

Design # Safety Strength Size Ease of Access Total
1 3 3 1 2 9
2 2 2 3 3 10
3 3 3 2 2 10

It’s a draw! However, we have decided on concept design 2 because of the appeal of the design and the compactness. Since this swing may end up in common areas in the house, we thought the design should be appealing.

Overview of Selected Design

The frame design that we have chosen is the c-frame design that has 2 support bars in the back. After considering all the possible designs, we think this would suite the families needs most. This design will give the family a lightweight, movable, and aesthetically pleasing frame for the child.

We would like to make the frames height adjustable and the long portions of the frame to disassemble so that the frame can be fitted and moved to different rooms throughout the house. To accomplish this, we will be using T-handle locking quick-release pins with lanyards to pin all the tubing together in combination with telescopic steel tubing.

We are considering making the frame out of 1.75″ and 2″, 0.105″ wall square steel tubing. The alternative is round 1″ and .75″ OD steel tubing with a wall thickness of 0.08″. The square tubing wall thickness is more desirable because of the frames height and weight ratings.

Since the swing will be made for linear and circular motions, a ball bearing swing hanger will be added at the top of the frame to mount the swing on. This should provide the family a long lasting and smooth ride of the swing no matter the direction.

We are also going to modify a platform swing to have heavy duty 3″ hook and loop fasteners to secure the inclines or chair supports for the child while it is attached to the swing. The idea behind this is to allow the parents to easily interchange the desired position for the child.

Engineering Analysis 1

For this analysis 2″ square tubing steel with 0.105″ wall thickness was stressed with a 400 lb force at the top of the 90″ tall frame. This single frame had a displacement of 2.978 cm. Since the final design will have 2 bars, less deflection should be expected.

Engineering Analysis 2

This analysis was done with the same size steel tubing as the previous analysis. The model used has 2 support bars with added braces. The stress analysis showed a 1.156 cm flex in the frame. Keep in mind that the model that was stressed is not a perfect replica of the actual frame design. The actual frame design will have a strong build to it.

Bill of Materials


2021 Fall