Elora Ghosh - 3D Printed Inflatable Balloon

3D Printed Inflatable Bladder

Project Overview

Modeled, built, and evaluated 3D printed bladder and shell design as small-scale prototype for emergency rescue device

Project Duration

3 months

Skills

Additive manufacturing, load analysis

Design Requirements

Bladder

Shell

Slim and expandable, able to fit in tight spaces
Able to inflate to 1.25 psi
Elastic, easily expandable and contractable
Minimal to no porosity
Create an effective seal

Conform to bladder curvature
High strength to weight ratio
Protect bladder from sharp contact points
Reliable points of flexure for repeated use

Existing Solutions

Jaws of Life

Forcible Entry Tool

While effective, these solutions require a gap wide enough for the jaws to fit into, usually about 4 inches, making them unsuitable for tight spaces. Existing devices are are also currently limited to metallic or hydraulic devices, which lack either flexibility or rigidity.

The bladder-shell design allows for a combination of the shell's rigid properties while also utilizing the flexibility of the bladder. Additionally, the use of additive manufacturing allows for lower-cost, customizable, application-specific structures, and those with orthotropic and functional material properties to aid better load supporting applications.

Loading Calculations

Moment about Point O (hinge)

Weight of car door (Wd)= 100 lbs Td = Door moment about point O

Area of bladder (Ab) = 40 in2 Tb = Bladder moment about point O

Td=Wd⋅L2

Tb=(Ab∗P)∗L1

Wd∗L2=(Ab∗P)∗L1

P=(Wd∗L2)/(Ab∗L1)

L2=0.5∗L1

P=1.25psi

Given that this design is a 1:10 scaled prototype, the load weight is 10 lbs.

Simulation

Displacement Simulation (Shell)

Static stress simulations were performed on the shell to validate the design's ability to lift the required load. An example of this simulation with a 10 lb load is shown, with the maximum deformation of 0.0528 inches being at the center.

Empirical Testing

Test Setup

Theoretical vs Empirical Deformation

Loading in 2.5 lb increments, the shell structure maintained a maximum deformation of 0.048 inches at 10 lbs, similar to the simulation predicted deformation of 0.0528 inches.

Below, the device is seen lifting a garbage bin of approximately 10 lbs.

Final Prototype Before Inflation

Final Prototype After Inflation

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