Development of the Mechanical Battery Texas A&M University – Kingsville Javier Lozano – MEEN Senior Luis Muratalla – MEEN Junior Eli Hatfield – EEEN Sophomore Gary Garcia – MEEN Freshman Richard Rivera – MEEN Freshman Jonathan Boehm – CEEN Freshman Faculty Advisor – Dr. Larry Peel

Project Background Design a safe, efficient mechanical battery that stores energy in a mechanical form, for use on the space station. Energy will be stored into Fiber Reinforced Elastomer composites. Rechargeable and portable form of energy storage.

Design Objectives Battery must be lightweight, compact Must be free of hazardous chemicals and toxic materials Have an energy density near or above that of an electrochemical battery Must be rechargeable electrically and manually Mechanically stored energy with an electrical energy output Prevent overcharging and battery failure

Semester Objective Complete the frame Complete Design layout Create solid models –Brake –Clutch –Bearings Meet Deadlines –College Station Presentation –End of Semester report Produce Deliverables –Semester Presentation –Report to NASA mentors –Report to College Station

Project History The team went from a smaller battery to a larger battery –Easier Fabrication –Higher energy density From having the strips in torsion to tension Analyzed composite strips to compare between circular torsion, rectangular torsion, and rectangular tension Initial dimensions.4” x.8” x 13” in torsion Optimal Fiber Orientation for best combination of elasticity and stiffness.

Current Design

Current Work Incorporation of Brake into the system Attempt to alter motor to strip gear ratio Structural Analysis –Frames –Mounting plates Further Analysis on Composite Strips Test all components of the electrical portion

Gearing System Clustered Design –Motor Gear –Generator Gear –Composite strip gear –Intermediate gear –Engagement gear Engagement arm –Engagement gear on end allows engagement of either motor or generator Gear Ratio Information –2:1 Ratio from Motor to shaft –0.25:1 Ratio from Shaft to Generator Motor Gear Engagement GearGenerator Gear Composite Shaft Gear Intermediate Gear Engagement Arm

Braking System Electromagnetic Brake –Use Mechanism to stop and lock Composite Strips in the stretched position Clutch –Use electromagnetic brake as clutch –Benefits Single Unit Less Controllers Lighter

Composite Strip Design Strip dimensions 2.25” x.1” x 15” IM7 Carbon fibers with a polyurethane RP 6442/fr 1040 matrix Ply angles tested +/-45, +/-60 or +/-75 Elements able to stretch 150% A time delay between stretching and releasing causes energy loss.

Energy Data

Energy Loss Data Both Started at 100%

External Frame An aluminum frame covered by a composite skin Current dimensions –24” x 14” x 8” Aluminum angle frame –Thickness of 1/8” –1” x 1” leg length Frame adds mounting capability Composite Skin provides stiffness, strength and safety

Building The Frame Bolt Vs. Weld –Vibration –Strength –Re-buildable Bracket Design Frame Corners –Eliminate Offset –Better Fit

Internal Mounting Fixture Provides mounting surface to attach parts Provides extra support Provides mounting of “rollers” for the strips to fully stretch more easily Separates gear train from internal parts

Completed Solid Model

Energy Conversion Purpose –Convert elastic potential energy to kinetic energy, to electrical energy and vice versa Components –Electric Motor –Generator –Clutch –Brake

Power Generation 12 VDC, 20 amp output Charge Batteries Power 12 volt DC equipment

Re-charge System Recharging –Easy recharges mechanical battery (Stretches composite strips) –Operate at 120 VAC or 24VDC Motor Specifications –24 VDC –1/3 HP –11.7 in lbs Torque Problems –Weight and size –Rotational speed

Current Schedule

Work To Come Possibly revise electrical portion Finish Building the System –Finish Building Frame –Install internal components –Incorporate Electrical Portion Test and Analyze results Attempt to Refine Design

Conclusion The fabrication of the frame is almost complete The team decided to weld parts of the frame vs. bolting Completion of gear analysis excel program –2:1 Ratio from motor to composite strip shaft –0.25:1 Ratio from composite strip shaft to generator Material relaxation is an issue with the strips Likely will have much lower energy density than expected in battery. Battery is best suited for high intensity low duration energy output.

Special Thanks Space Engineering Institute Magda Lagoudas Dr. Judith Jeevarajan Dr. Larry Peel Mr. Dustin Grant NASA (Prime Grant No. NCC9-150) TEES (Project No C3) Texas A&M University – Kingsville TAMUK staff and faculty

Any Questions?