Egress System Design Project for Mira A cooperative project of The Oregon Zoo and Portland State University.

Egress System Design Project Egress System Design Project for Mirafor Mira

A cooperative project of A cooperative project of The Oregon Zoo and The Oregon Zoo and

Portland State UniversityPortland State University

Mission Statement:Design a device which will allow Mira, a blind

elephant seal, to exit her pool habitat without raising the water level.

How am I going to get out of here?

Product Design SpecificationsProduct Design Specifications

Allow Mira to exit pool without raising the water level.Allow Mira to exit pool without raising the water level. No Major Aesthetic or Physical Changes to habitat.No Major Aesthetic or Physical Changes to habitat. Preferably Removable (and easily storable)Preferably Removable (and easily storable) Manageable by two trainersManageable by two trainers Five year lifeFive year life

First Ramp Design ConceptFirst Ramp Design Concept

Clears Beach headClears Beach head

Approx. 70 degree Approx. 70 degree ramp pitchramp pitch

Provides mechanical Provides mechanical advantageadvantage

Extends existing Extends existing beach slope surface beach slope surface area for Mira to exit area for Mira to exit water.water.

Mira’s BiomechanicsMira’s Biomechanics Propels herself with flippersPropels herself with flippers Moves body along much like an inch wormMoves body along much like an inch worm With traction, she can negotiate much steeper With traction, she can negotiate much steeper

slopesslopes

Second Design Concept

• Reduced distance of 70 degree pitch to 10 inches

• Allowed Mira a foothold to advance up the 70 degree portion of the deck

• Stress concentrations at bend made the design weak

High

Stress

Design OptimizationDesign Optimization

Gusset Tube was added to take up stress in bend.Gusset Tube was added to take up stress in bend. Dual extension legs reduced to one for reduced Dual extension legs reduced to one for reduced

weight.weight. Some bends were replaced with mitered and Some bends were replaced with mitered and

welded joints.welded joints.

Design OptimizationDesign Optimization

Traction strips were added for Mira to push-off ofTraction strips were added for Mira to push-off of Polyethylene decking was reduced to ¼ in thickness to Polyethylene decking was reduced to ¼ in thickness to

reduce weight by 40 poundsreduce weight by 40 pounds Gusset tube was moved to bottom to be in compression Gusset tube was moved to bottom to be in compression

and relieve bend angles.and relieve bend angles.

Fabrication BeginsFabrication Begins

Fabrication was done by student team.Fabrication was done by student team. 2 x 2 x ¼, 6061-T6 tubing could not be 2 x 2 x ¼, 6061-T6 tubing could not be

bent without annealing.bent without annealing. Welding the aluminum will create heat-Welding the aluminum will create heat-

affected zones which will weaken it to less affected zones which will weaken it to less than half of the original T6 yield strength than half of the original T6 yield strength (safety factor drops to 0.85).(safety factor drops to 0.85).

The FixThe Fix

Aging the aluminum after welding would only recover 7-Aging the aluminum after welding would only recover 7-10% of annealed properties, while the unaffected areas 10% of annealed properties, while the unaffected areas would over-age and lose strength.would over-age and lose strength.

Decided to cut and weld the apparatus, and heat treat it.Decided to cut and weld the apparatus, and heat treat it. No oven in Portland was large enough to accommodate the No oven in Portland was large enough to accommodate the

entire assembled structure (24in x 44in x 86in).entire assembled structure (24in x 44in x 86in).

Still FixingStill Fixing

Gusset plates were added to raise the safety factor to 2.4 so the Gusset plates were added to raise the safety factor to 2.4 so the welding could be done and the s.f. would only fall to 1.25 (without heat-welding could be done and the s.f. would only fall to 1.25 (without heat-treatment).treatment).

‘‘Stack Metellurgical’ could heat treat pieces up to 60 in long.Stack Metellurgical’ could heat treat pieces up to 60 in long. The structure was to be cut at low stress planes so it could be welded The structure was to be cut at low stress planes so it could be welded

together after the critical welds were heat treated and artificially aged.together after the critical welds were heat treated and artificially aged.

Proof of ConceptProof of Concept

Ramp was tested for impact with human Ramp was tested for impact with human subjects.subjects.

Ramp was statically tested with impact Ramp was statically tested with impact forces on ANSYS.forces on ANSYS.

FEA AnalysisFEA Analysis

Minimum Safety Factor under maximum Minimum Safety Factor under maximum loading > 1.5loading > 1.5

Meeting PDS RequirementsMeeting PDS Requirements

Easily StoredEasily Stored RemovableRemovable

Meeting PDS RequirementsMeeting PDS Requirements

Easily handled by two trainers.Easily handled by two trainers. No major aesthetic or physical changes.No major aesthetic or physical changes.

Can Mira Get Out?Can Mira Get Out?

QuestionsQuestions