Coffee Table MMAE 445 Design Project

Tricia Hale | Wojciech Lukaszczyk | Gerard Simon Prosper | Yash Surana | Alan Grossman

Initial IdeaCoffee tables have been around for a long time, and they have kept their basic

function of providing surface storage. However, internal storage is an issue.

The solution is to place a concealed compartment that would allow for surface

and internal storage with more convenience.

Initial ConceptConcept: A coffee table with a

middle section that rises to the

surface when pressed

Torsional spring and damper

system used to lift middle section

Middle section made to hold bottles

and glasses

Revised ConceptA spring damper system was too

complex for the time allotted.

A gas spring that can have a fixed

height seemed much easier.

The gas spring needed to have the

right amount of force to be

compressed, but also raise the

column.

Gas SpringsGas springs are easily

chosen by using the

configurator provided

by Bansbach.

The design was very

universal with the

addition of threads.

Engineering DrawingA drawing was made to create initial

dimensions, and was used to create a

3D model in Solidworks.

The dimensions were chosen to

represent a good height when sitting.

The center column would provide

support while concealing the lifting

mechanism.

Material SelectionAll long, thin surfaces are made from

high quality plywood.

Legs would be made from pine studs.

Anything that is not rectangular will be

made from aluminum.

Solidworks RenderingInitial renderings

provided a

aesthetically pleasing

coffee table.

It was time to create

an FEA model to see

if stresses were not

exceeding yielding.

1st Attempt at FEAOur initial simulation

contained errors in

that the applied loads

and boundary

conditions were not

accurate.

2nd Attempt at FEAWe got closer to what was

needed by applying the correct

boundary conditions.

Our loading was still inaccurate.

A point load used instead of a

distributed load over a certain

area.

2nd Attempt at FEAThis Von Mises stress shows a

maximum stress of 10MPa

The yield strength for this

material was 31 MPa

The Von Mises stress of 10 MPa

was far lower than the 31 MPa

yield stress.

An area of 4 inches by 12 inches

was created to represent

someone’s feet. The 350 lbs

was distributed evenly across

this area.

A much more accurate

representation of potential

stress was created.

3rd Attempt at FEA

The newly obtained Von Mises

stress was 8.2 MPa which was

far lower than the yield stress

of 31 MPa

This shows that our design can

handle the load safely

3rd Attempt at FEA

Solidwords model analyzed in Abaqus CAEUsing distributed instead of the

concentrated force, we

obtained a deflection 1.2mm

According to experience, this is

similar to what was expected.

Solidworks design of center column A center column was created

to bring up the various items

contained within the table.

The top would be the cutout

of the top surface.

The squares on top represent

the area that the hands would

cover when pushing the

center down.

Center Column Stress AnalysisVon Mises stresses show that

our stress was about 75.7

ksi.

The yield stress was at about

87ksi for the center rod.

Center Column DeflectionThe deflection came out to only

be 0.4 inches at the lowest

extreme.

The one handed push seemed

to work well and the two

handed push analysis was

deemed unnecessary.

Assembly AnimationThe table appears to be a regular coffee table until the center extends

upwards, revealing a storage compartment.

Special thanks to Tricia’s

boyfriend for sharing his

SOLIDWORKS wisdom.