P16221 – FSAE Shock Dynamometer Preliminary Detailed Design Review November 17, 2015

P16221 – MSD Team Aung Toe – EE Jim Holmes – EE Sal Fava – ME Project Manager Sal Fava – ME Chief Engineer Chris Batorski – ME Facilitator Andrew Dodd – ISE

Agenda Address concerns from System Level DR System Level Design Flowchart Updates Engineering Spec Updates Current Bill of Materials Safety Considerations User Interface (software) Model Overview Mechanical Systems Analysis Electrical Schematics Risk Management Project Plan

Background: Problem Statement The goal of this project Design a device to characterize dampers Capable of supplying a displacement input profile in time and measuring force, displacement, and temperature responses of a damper

Resolved Issues from Sub-system Level DR Maintenance interval concerns Based on purchased components and fatigue life. For example, bearing life. Will develop a maintenance and assembly guide Safety enclosure really necessary? Yes, designed to keep fingers out of pinch points as well as protect from shrapnel in the event that something breaks Potential racking issue Assembly is very symmetrical Connecting rod introduces less than 200lbf out of plane

Issues from Sub-system Level DR Rust concerns on stand Steel components will be painted Potentially make mast out of aluminum How did you arrive at the selected board and microprocessor Based on data transfer needs, ADC resolution and 32 bit processing power Frame deflection Low priority-will investigate for DDR

Issues from Sub-system Level DR Magnetic vs optical isolators Optical isolators offer sufficient speed Hire electrician for 208V Need to finish motor circuit to request a quote Test plans using function generator for data transfer Will define after software is written Start to outline rotary design Design is now based on rotary design Never got a definitive answer on ball screw actuator

Open Issues From Last Review What will keep the dyno from “walking across the floor” while it is running? Initial estimate and calculations complete Develop an Engineering Analysis vs. Risk vs. Verification Test metric to make sure everything is covered. Still in progress, has been started Any function in the system functional block diagram with only one child should be combined into one block Low priority, still in progress

Engineering Requirements

BOM

Predicted Costs

System Level Design Flowchart

Subsystem Design Safety Goals of sub-system: Protect user from serious damper failure Not impede user activities within working zone Low cost Important features Enclosure Emergency Stop Switch Safety Door Lock Safety Circuit

Safety Sub-System Overview Major Components Interfaces Aluminum Extrusion Frame Minitec 45x45 F Plastic Shielding Polycarbonate sheeting Door Safety Latch Safety Circuit test plan Test stand base Bolted to base Work Area Surrounds the masts and test area Emergency Stop Switch Will be mounted to the frame

Safety System Enclosure Design Overall Dimensions Height: 48 in Depth: 12 in Width: 36 in Bolted to table 8X 5/16-18 Bolts Held together with custom designed brackets An effort to reduce cost of the system

Safety System Door Design Overall Dimensions Height: 46 in Depth: 12 in Width: 32 in Currently Designed with Standard MiniTec hinges and handles Could replace with custom parts

Safety System Custom Plates Top Plate Used to hold top of enclosure to the uprights Thickness: ¼ in Material: Aluminum Bottom Plate Bolts the enclosure assembly to the test stand Thickness: 7/16 in

Safety System Door Interlock Used to lock the enclosure when test is being run IDEM 16.5mm Mount Safety Switch: $29.50 Actuator Key: $11.50 Available from Automation Direct

Subsystem Design Software Interface Goals of Subsystem Provide user with a way to control and program the test stand Post processes the raw data and saves it in .csv format Important Features Car Parameter Inputs Track Data/Profile Selection Post Processing Graph Display

Software Interface Efficiency (83%): Took 6 hours to perform this task as it stands. Would take approximately 5 hours to redo.

Software Interface Calculations Equations Variables 𝐾 𝑤 = 𝑘 𝑠 ∗ 𝑀𝑅 2 𝐾 𝑟 = 𝑘 𝑡 ∗ 𝐾 𝑤 𝑘 𝑡 + 𝐾 𝑤 𝜔 𝑠 = 1 2𝜋 𝐾 𝑤 𝑚 𝑠 𝜔 𝑢𝑠 = 1 2𝜋 𝐾 𝑤 + 𝐾 𝑡 𝑚 𝑢𝑠 𝑐 𝑐𝑟𝑠 =2 𝐾 𝑤 + 𝑚 𝑠 𝑐 𝑐𝑐𝑢𝑠 =2 𝐾 𝑤 + 𝐾 𝑡 ∗ 𝑚 𝑢𝑠 Kw = Wheel Rate Ks = Spring Rate MR = Motion Ratio ωs/us = Natural Frequency (sprung/unsprung mass) ms/us = Mass (sprung/unsprung) ccrs/us = Critical Damping (sprung/unsprung mass)

Software Interface Results (Characterization)

Overall System Geometry From SSLDR

Load Cases/Constraints 350lb marginal, 500lb ideal vertical force through the actuator, damper and into the crossbar FOS of 2 used in all calculations Design for stress levels under the endurance limit, infinite fatigue life Welded structure Knockdowns Aluminum weld-area strength= 0.5 base material Steel weld-area strength= 0.8 base material Ideally every component in a system would have Margin=0 Positive = over-designed Negative = under designed

Analysis: Isolator Sizing Efficiency: Isolator Sizing – Initially took 1 evening, could repeat in 1 hour.

Analysis: Mast Sizing

Analysis: Clamp Load

System Forces

Gearmotor Selection Efficiency: Gearmotor Selection - Initially took 3 days; could repeat in an hour. Efficiency (3%)

Gearmotor Selection

Actuation Assy Efficiency ~5%

Interfaces/Clearances Over 1.5in between damper and slider Small clearance between clevis and damper

Forces

Shoulder Bolt Sizing Determine the min diameter shoulder bolts that can be used in each location

Impulse High Impulse load of 1800 lbf Shear Pin needed Efficiency 37.5%: Took about 4 hours Could repeat in 1.5 hours

Preliminary Bearing Selection SKF NU 202 ECPHA Far exceed dynamic load rating Fatigue rating needs to be further evaluated

Arduino Dataflow

TI ISO124 Analog Isolator

VISHAY CNY17 Digital Isolator

Electrical System Schematic

Electrical Wiring Schematic

Power Management

Power Management

Serial Interface Test

Proof of Concept: Testing so far IR sensor test 𝑇𝑒𝑚𝑝(𝐶)= 𝐴𝐷𝐶𝑟𝑒𝑎𝑑𝑖𝑛𝑔(𝐷𝐸𝐶)∗ 𝑟𝑒𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 𝑚𝑉 2 𝑛 −𝑜𝑓𝑓𝑠𝑒𝑡(𝑚𝑉) 𝑆𝑒𝑛𝑠𝑖𝑡𝑖𝑣𝑖𝑡𝑦 ( 𝑚𝑉 𝐶 ) = 348∗ 5000 2 12 −400 30 =0.82𝐶 Additional testing required for higher temperature

Tests Planned Analog Isolation Digital Isolation Safety loop test UART and PC interface test

Theoretical Models: Serial Interface (UART) Serial Speed Analysis Inputs Memory Requirements (64 bits of data in 0.002s) Output 32,000 bits/s Conclusion- feasible baud rates: 38,400 56,000 115200 https://atarilynxdeveloper.files.wordpress.com/2013/09/image.png

Risk Assessment

Risk Assessment

Updated Project Plan

Questions? http://www.jobinterviewtools.com/blog/wp-content/uploads/2010/01/dreamstimemedium_19473030-300x300.jpg