ME 351A PROJECT

Team members

Ankit Shrivastava (11113)

Ankit Yadav (11115)

Ahsen Parwez (11416)

Deepak Dalakoti (11235)

Shivam Patel (11683)

Anurag Bhatt (11135)

Project Title – Transporters

OBJECTIVE

Design of transporter system in Southern Labs

Analyzing critical failure locations of the assembly

Estimating present load capacity of the machine

Proposed design changes for a load of 3 tonnes

SUB SYSTEMS

Pneumatics and Pulley Primarily lifting mechanism

Pneumatic piston cylinder arrangement

Powered by motor

Main Frame Supports carriage and pulleys

Safety features like anti roll bar

Carriage Platform reinforced by square steel bars

Connected to chain and pulley assembly

Design Specifications

FBD and Analysis of sub-system

Is allowable load under 3 tonnes?

Identify critical locations with n =3

Proceed to next sub system

Design alterations

NO

YES

Choose minimum of all loads as the rated load

PNEUMATICS AND PULLEY

Possible modes of failure

Rupture of pneumatic cylinder Buckling of piston rod Weld failure of Pulley shaft T section yielding Chain Design

ESTIMATING CRITICAL LOADS

Failure Mode Critical load with n = 3 (in tonnes)

Rupture of pneumatic cylinder 10.72

Buckling of piston rod 81

Weld failure of Pulley shaft 3.05

T section yielding 9.9

Chain failure ASTM 60 designed for 3 tons

Critical element - pulley shaft Maximum allowable load = 3.05 tonnes Satisfies design requirement of 3 tonnes No design modifications required

MAIN FRAME

Modes of failure

Failure of load carrying bar Weld failure of welded chain Anti roll bar failure

ESTIMATING CRITICAL LOADS

Modes of failure Critical loads with n =3 (in tonnes)

Failure of load carrying bar 1.1

Weld failure of welded chain 9.8

Anti roll bar 4.2

Critical location – load carrying bar Maximum allowable load < 3 tonnes Design changes required

DESIGN CHANGES FOR WEIGHT CARRYING BAR

Increase weld length and leg size Maximum Load is 2.4 tons for h =5mm and d = 5mm

Maximum length and leg size limited by dimensions of bar

Change material 440 Q&T steel

Maximum load is 7.32 tonnes

Economically unfeasible

Change weld pattern Square weld

Maximum load = 3.26 tonnes

Most feasible solution

Compromised Factor of Safety Measure of last resort

For n = 2 , critical 4.8 tons

CARRIAGE

Modes of failure

Weight sharing by square reinforcing side bars

Shear failure of reinforcing side bars

ESTIMATING CRITICAL LOADS

Modes of failure Maximum load with n = 3 (in tonnes)

Weight sharing by square reinforcing side bars

26.42

Shear failure of reinforcing side bars 6.73

Critical location – shear failure of reinforcing side bars

Maximum allowable load = 6.73 tonnes Satisfies design requirement of 3 tonnes No design changes required

FINITE ELEMENT ANALYSIS

Analysis done using design principles was cross checked using Finite element packages commercially available.

Inventor was used to create a CAD model of the critical systems and analysis was done.

We plotted the factor of safety for the structure while taking load as 3 tonnes.

Also, displacements of critical elements were plotted to check assumptions made during theoretical analysis

LOAD CARRYING BAR

LOAD CARRYING BAR

LOAD CARRYING BAR

LOAD CARRYING BAR

CARRIAGE WELDS & BENDING

CARRIAGE WELDS & BENDING – Y displacements

CARRIAGE WELDS & BENDING- Safety factors

CARRIAGE WELDS & BENDING- Safety factors

DESIGN SHORTCOMINGS & PROPOSED CHANGES

Exact length of Piston rod unknown

Novel Use of chain with pulley modelled as pulley with cable

Mixture of butt & fillet welds in reinforcement bars taken as all fillet welds (inherently conservative as fillet welds are weak)

PROPOSED CHANGE :

Load carrying bar most critical & fails at weld to connecting plate

Design change made : weld pattern change

Alternative: Add reinforcement to bar like in a truss for load sharing and larger capacity enhancement and reliability

THANK YOU