MDP Final Design Report

8/4/2019 MDP Final Design Report

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UNIVERSITY OF SOUTH AUSTRALIA

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Student Name (Print clearly) UniSA Email ID

1. Christian-Raymund Sarmiento [email protected]

2.Deepak kumar [email protected]

3.Rajeesh [email protected]. Chen, Jiajie [email protected]

Course code and title: (MENG 2004) Mechanical Design Practice

Program Code: School: School of Advanced Manufacturing

and Mechanical Engineering

Day, Time & Location of Tutorial/Practical: Thursday, 4-7 pm, J2-25

Course Coordinator: John Fielke Tutor: John Fielke

Extension granted (Yes/No): Due Date: Friday 16 September 2011

Assignment number & topic: Assignment 1 – Design of a Mechanism

We declare that the work contained in this assignment is our own, except where

acknowledgement of sources is made.

We authorise the University to test any work submitted by us, using text comparison

software, for instances of plagiarism. We understand this will involve the University or its

contractor copying our work and storing it on a database to be used in future to test work

submitted by others.

We understand that we can obtain further information on this matter at

http://www.unisa.edu.au/learningadvice/integrity/default.asp

Signed: Date:

1. Christian-Raymund Sarmiento 17/09/10

2.Deepak kumar 17/09/10

3.Rajeesh 17/09/10

4. Chen, Jiajie 17/09/10

Date received from student Assessment/grade Assessed by:

Recorded: Dispatched:





Mechanical Design Practice

Design Project

University of South Australia

School of Advanced Manufacturing and Mechanical Engineering

MENG 2004 Mechanical Design Practice

Assignment 1 - Final Report

Design of a Lifting Mechanism

Course Coordinator: Associate Professor John Fielke

Due date: 16th September 2011

http://www.unisa.edu.au/ame/

http://www.unisa.edu.au/ame/




Design Project

Executive SummaryDesign

This is the chosen design for the lifter which has

capacity to lift 100kg at an inclination of 450 to

the horizontal (Considering if the lifter being

used in mountains and hilly areas). The

mechanical advantage of the system

incorporates with the use of hydraulics which

allows us to put small input and obtain large

output. In fluid power, hydraulics is used for the

generation, control, and transmission of power

by the use of pressurized liquids. It‟s a low

maintenance system which is controlled by

fluids and a power screw. The operating effort

used in lifting the Mass is at bare maximum thatis 400N such that with hydraulics (by foot) and

the lifter travels to and from the car boot with the

help of parallel tracks installed inside. The operating effort applied with hands is 200N.

Figure 1- Lifter Mechanism

Figure 2 - Lifter Installed in Boot Space of the Safari Car




Design Project 4

ITEM NO. PART NUMBER DESCRIPTION QTY.

1 Car Boot Safari car with parallel tracks installed inside 1

2 Frame Rectangular tubes built with welding operation 1

3 Fixture Fastened on the frame with two screws each 4

4 Link1 Freely rotating on the cylindrical surface of Fixture 2

5 Link2 Freely rotating on the cylindrical surface of Fixture 2

6 Lifting Platform Accommodated with 2 no. of Link1 and Link2 each 1

7 Hydraulic Arm (M) Attached to the Frame which enables linear motion 1

8 Hydraulic Arm (F) Attached to two Link1's to provide circular motion 1

9 Pin(Hydraulic Arm) Provides rigid connection on the frame 1

10 Pins(Lifting Arms) Holds the Lifting platform with cylindrical fits 4

11 Bolted Part Fastened with 4 bolts on the rear side of frame 1

12 Welded Part Welded on rear side of the Frame 1

13 Power Screw Mounted between Bolted and Welded Part 1

15 Rings(Fixture) Provides a back-up for fixtures and Link1 4

16 Hydraulic Cylinder Arm Used to advance with low input manually 1

17 Hydraulic Cylinder Cylinder used to pressurize liquids to Hydraulic Arms 1




Design Project

Isometric View of Main Assembly

2

3

4

5

6

7

8

9

10

10

11

12

13

16

17

14

Figure 3 - Isometric Projection




Design Project 6

PARTS MATERIALS SPECIFICATIONS/DIMENSIONS

Frame 2014 T6 Aluminium Alloy 1074 mm × 1008 mm × 80 mm,

Fixture 2014 T6 Aluminium Alloy 74 mm × 74 mm × 100 mm

Link1 AISI 304 74 mm × 444 mm × 40 mm

Link2 2014 T6 Aluminium Alloy 74 mm × 444 mm × 40 mm

Lifting Platform RHS 1040 Steel alloy Cold Rolled 1008 mm × 1172 mm × 600 mm

Hydraulic Arm (M) - Φ 50 mm × 227

Hydraulic Arm (F) - Φ 30 mm × 227 mm

Pin(Hydraulic Arm) AISI 304 Φ 40 mm × 70 mm

Pins(Lifting Arms) AISI 304 Φ 40 mm × 80 mm

Bolted Part 2014 T6 Aluminium Alloy 137.5 mm × 148.5 mm × 200 mm

Welded Part 2014 T6 Aluminium Alloy 230 mm × 215 mm × 137.5 mm

Power Screw Stainless Steel

Square thread, Double start, dm (30mm), dr (23 mm),

length = 1074 mm

Rings(Fixture) 2014 T6 Aluminium Alloy Φ 65 mm × 20 mm

Hydraulic Cylinder

Arm AISI 304 1225 mm × 115 mm × 80 mm

Hydraulic Cylinder - Maximum Pumping Pressure Capacity = 46 MPa




Design Project 7 Figure 4 - Poster




Design Project

Table of Contents

Executive summary 3

Description 3

Rendered image 4

Isometric View 5 Bill of materials 6

Poster 7

Table of contents 8

The design of brief 9

The “Group Charter” 10

Concept map 11

Task/roles 12

Alternative ideas 13

Design 1 13

Design 2 15

Design 3 18

Design 4 20

Design documentation 23

Power screw design 25

Bolted joint design 27

Welded joint design 30

Lifting platform design 33

Pin design 35

Material cost calculation 41

Appendix 42




Design Project

Design Brief

Mobility scooters have been a beneficial aid in helping senior and disabled people

travel from location to location. The design of mobility scooters have given many

consumers who are who are unable to walk around an opportunity to travel with ease.Since its creation in 1968 by Allan R. Thieme () mobility scooters has been an

essential part of many people‟s lives.

Recently with the UniSA company commencing business on July 2011, it is given at

hand that the company has given responsibility to UniSA Design Group C1. Pty Ltd.

The group consists of four designers to develop another approach in aiding the

consumers of mobility scooters. The task is to develop a hand operated system for

loading a mobility scooter into a car. The group is to also choose appropriate

materials, so that money is not lost. The company would also like to sell as many of

the designs as possible.

The design group needs to follow a few needs in order for the design to be

applicable. By approaching a method of selecting suitable types of cars and mobility

scooters, the initial design concepts must be mechanically operated and proven to lift.

The operating specifications must also be followed stating a maximum operating

effort of 200 N by hand and 400 N by foot. This is reasonable due to the

disadvantages of senior and disabled users. By developing the initial concepts and

proceeding to the final appropriate design, the design group must also document the

final design; its materials, total cost and recommended retail price (RRP).




Design Project

Group Charter

It is highly important that each group member attends all group meetings, to ensure

that the group is up to date with work.

Meetings are not to be missed.

If so the group member must inform the group members via email, phone call, text

with a valid reason.

Each group member needs to be prepared and familiar with the given task to make

certain that the time used is not wasted.

Before and after group meetings the progress of the group should be observed, to

determine that the group is heading towards the right path.

It would be easier if each group member spoke out there differences of a topic sothat a better solution can be found.

Workloads are divided equally between the group members.

Each group member is responsible for the task given at hand.

Group members need to familiarise themselves with the theory and purpose of the

project. This is to ensure that no one in the group struggles or slows down the

progress.

Group members are responsible for their calculations, and by approval can have it

re-checked by another group member.

It is essential that all group members‟ work together to ensure the workload is

completed on time.

Failure to follow these rules will most probably result in a reasonable peer

assessment.




Design Project

Concept Map

Below is the concept map outlining a step by step guide towards producing a lifter for

mobility scooter.




Design Project

Task/Roles

Name Role/Designation Tasks

Deepak Kumar Design Engineer

Individual Force Balance Calculations

Group Concept Map

Executive Summary

Statement of Task/ Roles

Individual Concept Map

Project Compiling

A3 Poster

Power Screw Design

Material and Systems Cost

Chosen Design Cad Model & Drawings (Solid Works)

Rajeesh Project Engineer


Group Concept Map

Table of Contents

Bolted Part Design

Welded Part Design


Project Compiling

Christian Production Engineer


Group Concept Map

Design Brief

The “Group Charter”


Project Compiling

PeterMaintenance & Service

Engineer


Lifting Platform Design

Pin Design





Design Project

Alternative Ideas

Each group member was given responsibility to develop designs that would aid

consumers in placing a mobility scooter onto/into a car. The designs are presented

as CAD models developed from Solid Works. The force balance diagrams and

calculations of each design are to be proven, and that the design also follows the

specifications to be applicable in the project. By applying research on certain

vehicles and scooters, it was decided that the types of cars used would be wagons

and safaris. Medium size scooters have also been chosen for this project.

Design 1

Design one consists of four bars, two on each side all attached to a central shaft.

Also placed onto the shaft is the compartment or surface in which a mobility scooter

is placed. The design procedure is fairly simple.

There are two ends of the design. One end is fixed which is placed close to the boot

of a safari or wagon. The other end is pinned with wheels that allow it to move

forwards and backwards.

Placed within the design is a welded body hydraulic cylinder. The cylinder is

attached to shafts placed between the bars of the design. The particular hydraulic

cylinder that would be used is a retracting cylinder. In other words the length of the

cylinder decreases when pressure is applied by the piston.

When the cylinder retracts, it causes the moving end to move towards the fixed end.

Since they are both connected to a central shaft, the height of the device increases

and the mobility scooter is lifted and also placed forward within the safari or wagon.

From there on the scooter can be pushed in.




Design Project

Assume that the average weight of a mobility scooter is 100 kg.

F1 = 100 kg * 9.81 m/s^2 = 981 N

Assume that the max height allowed for the device to rise is 50 cm. The minimum

height it can descend is 20 cm. When the hydraulic cylinder is placed within the

design, an appropriate total length before retracting is 60 cm. When the device is

high enough the new length of the cylinder is 30 cm.

By applying the law of energy conservation we get equation.

F (h1 – h2) = f(l1 – l2)

F = 981 N, h1 = 0.5 m, h2 = 0.2 m, l1 = 0.6 m, l2 = 0.3 m

981 N (0.5 m – 0.2m) = f(0.6 m – 0.3 m)

f = (981 N (0.5 m – 0.2 m)) / (0.6 m – 0.3 m) = 981 N

Therefore the force needed from the hydraulic cylinder is 981 N to operate the

device. Now assuming an input/output ratio of 1/5 for force gives us;

Input / Output = 1/5

Input = Output*(1/5)

Output = 981 N

Therefore Input = 981*(1/5) = 196.2 N

Depending on the pressure of the hydraulic cylinder the device can work. However

for this case by assuming a1/5, input/output ratio of a cylinder the device can in factlift the mobility scooter.




Design Project

Design 2

This design works on the principle of hydraulics and an effort is been made to reduce

the complexity of mechanism. The whole system is been mounted on the rear boot

of the car with pre-installed parallel tracks which guide the Frame. The motion of the

Frame is controlled by the power screw which is mounted on the rare side. The

power screw is mounted on two parts, out of which one is welded and other is

fastened with screws. The hydraulic piston is mounted on the Frame with the

conjunction of mechanical Pin. The Links (tip) is mounted on the Fixtures havingground surfaces (reamed surface). The links (root) is attached to the Lifting Platform

with the help of 4 finished (reamed) holes and 4 Pins. All Pins have ground surfaces

with two holes on one face to avoid rotation of the Pin itself. The hydraulic arm (male)

is mounted on the support of the Rings which is welded on Links 1 & 2. The

hydraulic piston is controlled by the pumping system which is rigidly attached at the

bottom of the care.




Design Project

Force Balance Calculations

Considering the maximum force condition such that a large distant force will make a

large effort applied and less distant force makes small effort applied.

Free Body Diagram Fd

D Fa

W β

C E Fc

(90- α)

A B

Given:

AB = 869.5, BC = 956, DE = 370, CE = 83

The only condition of maximum force Fd experienced by the hydraulic piston when

Link CE is perpendicular to face DE.

So β = tan-1(DE/CE) = tan-1(370/83) = 77.35o

α = tan-1(BC/AB) = tan-1(956/869.5) = 47.713o

Total Mass = Mass of the Scooter (Including Battery) + Mass of the Lifting Parts

Total Mass = 100 kg + 100 kg

Total Mass = 200 kg

W = Mass * Gravitational acceleration = 200 × 9.81 = 1962 N

Fa = 1962 / cos(90-α) = 2.65 KN

Fc = Fa cos α = 1.8 KN Fd = Fc / cos β = 8.15 KN

So the force acting on the hydraulic piston is 8.15 KN and now calculating the

pressure exerted on the hydraulic piston that is

P = Fd / (A - a) (Radius a = 12.5 mm, Radius a = 10 mm)

P = Fd / (π(12.5

2

- 10

2

)) = 46 MPa




Design Project

Force need to exert on the hand pump is 8.15 KN and it can be done by lever which

is 1225 mm in length.

8.15 KN F

55 1170

Taking moments at root of the lever

8.15 × 103 × 55 = F × 1225

F = 383.10 N (which is less than required effort of 400 N )

So 383 N on 1225 mm lever will do the job. It is the proof that with this design effort

is less than 400N with the foot effort.




Design Project

Design3

Main idea behind this design is to make a lifter which is safely attached to the car.

The platform is attached to the links and operated using a hydraulic cylinder.

Hydraulic cylinder is actuated using a hand pump and actuated using hand lever.

The effort is calculated to be 192N. The lifter can be fitted to ford falcon wagon or

any similar size wagons. Most of the scoter which are under 140kg, available in the

market can be lifted with this lifter.

Force Balance

200 700

150

1000

200 kg




Design Project

Total load to lift including mobile scooter and platform = 150 kg

Horizontal force

Vertical Force

N

Using a main hydraulic cylinder to lift the load, and total force on the cylinder is

√ =13198N

This force can be exerted on the main cylinder using a hand pump. Using a 50mm

cylinder and 20mm cylinder for hand pump

Force need to exert on the hand pump is 2111.68 Newton and it can be done by

hand lever which is 220mm length.

2111.68N F

20 200

2111.68 20 = 220 F F = 191.98N

So 191.8N on 220mm lever will do the job. It is the proof that with this design effort is

less than 200N with the hand.




Design Project

Design 4

This is one of the possible designs. Assume that, there is a 1000N load on the top of

the system. The maximum lifting capacity is 1m. firstly, we assuming that the weight

of this system is ignored. With the lifting table change the height for 1m the hydra

pump‟s arm will move 40cm. From the energy conservation, we have:

Mgh= fs and

h=1m

s=40cm

f2=mgd/s=2452.5N

We found that, if the pump power f2 is bigger 2452.5N. This system can be derived

by the hydraulic pump.




Design Project

Decision Analysis

Below is a table signifying a marking criteria/score of the conceptual designs. This is

part of the decision analysis so that a final component design is chosen.

Criteria Weight Design 1 Design 2 Design 3 Design 4

Score Total Score Total Score Total Score Total

Reliability 10 4 40 8 80 5 50 4 40

Complexity 2 8 16 8 16 8 16 7 14

Originality 2 4 8 10 20 10 20 4 8

Innovative 1 7 7 9 9 7 7 5 5

Weight 5 6 30 10 50 10 50 7 35

Low

Maintenance 7 7 49 4 28 7 49 7 49

Standard

Components 6 6 36 5 30 6 36 8 48

Ease of

Manufacture 2 7 14 5 10 7 14 8 16

Totals 200 243 242 215

Comments:

While rating the designs using the scoring method above, each designs score was

justified with given reasons.

Design one received a reliability score of 4. This was because the base of the device

seemed my smaller than the mobility scooter. There was disagreement that the

device would balance out. The bending moment at the central shaft created reasons

and made the platform unreliable. There is also a high probability of the scooter

falling off. The device was simple, however was stated not original. It is described tobe innovative utilising the hydraulic pump effectively. The device was assumed to be




Design Project

heavy therefore was a significant factor in the scoring. Parts are not available, and

the design does not have complex shapes to be manufactured.

Design two had a reliability of 8. However there was concern due to the probability of

breaking the arms and lifting platform. The mechanism does not look complex, and

was very original praised with an originality score of 10. The device was veryinnovative as it consisted of many mechanical components. The score of the weight

was given as 10. The reason was because the device was not needed to be handled

by a user instead its being held within the vehicle. The design however received

reasonable scores for low maintenance, standard components and ease of

manufacture. This was because some components such as the hydraulic cylinder

would need to be frequently oiled. Parts are also unavailable in the market. If the

parts break, they need to be manufactured. The components are also large which

brings an issue to manufacturing the parts.

Design three was similar to design two. The design received 5 for reliability because

the device was placed at the edge of vehicle. There was a disagreement that the

edge of the surface can hold the weight of the scooter. Also a force is applied to one

end of the device which can cause the device to break. The device was praised with

similar scores to design two. Again for design three some of the major components

are unavailable in the market and need to be manufactured. The parts are also too

big to be machined.

Design four received a reliability score of 4. This was because the device seemed

fragile and unable to lift the scooter. The device was not complex, and some groupmembers said it was not original. However the device was fairly innovative using

mechanical advantages. Again since the design had to be picked up weight was an

issue. But the weight was given as 7 because the design was described to be light.

The design seems to have a good low maintenance, and the materials look available

in the market. Manufacturing the design also looks easy.

Both design 2 and 3 had a close score with a difference being 1. Both designs

also had similar components. However by group decision design two was

chosen. This was because the components involved some very interesting

mechanical advantages.




Design Project

Design Documentation

Component Design Calculations:

In order to have a safe design the Component Strength must be greater than the

Actual Maximum Stress. In many cases there is a great deal of uncertainty on boththe values for the strength and the stress and these are accounted for using a

Design Factor or Factor of Safety [1]

Design factor, N =

Accounts for uncertainties concerning stress and strength:

Composition of materials

Variations in properties within a bar of stock

Effect of local processing on properties

Effect of nearby welds, shrink fits

Effect of heat treatment

Intensity and distribution of loading

Validity of loading model to represent reality

Intensity of stress concentration

Influence of time on strength and geometry

Effect of corrosion

Effect of wear

Uncertainty of other factors

The uncertainties can be broken down into:

Material reliability (Nm)

Workshop Accuracy (Nw)

Design load accuracy (Na)

Consequence of Failure (Ncf)




Design Project

The design factor N = Nm x Nw x Na x Ncf

So for hydraulic lifter design, using all ductile materials then Nm = 1.1

Most surfaces are machined, for higher safety we are selecting Nw = 1.0

Most situation are well defined, for higher safety Na = 1.2

Since the failure may cause injury to the disabled personnel operating Ncf = 3

Therefore design factor =

Factor of safety of 3.96 can be used for all major parts from these calculations.




Design Project

Power Screw Design

A Power (Lead) screw can be used in conjunction with split nut. They are the

most efficient, having the least friction, so they are often used for screws that carry

high power. Most preferred material for screw is steel and a coefficient of friction is

generally 0.1 for steel.

Let us consider a car is travelled to a hill station and now the car stopped at an

inclination of 45o with the horizontal because maximum a car can climb is 45

degrees. Only few cars can climb upto an angle of 60 degrees and it applies to only

few models of Audi. However Audi models are not economical to buy and use for the

lifting purposes. The economical cars which can make out 45 degree climbing would

be generally 4×4 drive.

α

F = Mg/sinα

m = 200 KG

So W = mg = 200 × 9.81 = 1962 N

α = 45o And F = Mg/sinα = 2452.5 N

For Self Locking screw the equation is

πfdm > L equation-

1

In the above equation „f‟ is the coefficient of friction, „dm‟ is mean diameter of the

thread and „L‟ is lead of the screw.

If d is the major diameter such that d = 30 mm

dm = 30 – L , f = 0.1

Solving the equation-1

π × 0.1 × (30-L) >L

L < 7.17, so let us assume L=7

http://en.wikipedia.org/wiki/Split_nut

http://en.wikipedia.org/wiki/Mechanical_efficiency

http://en.wikipedia.org/wiki/Friction

http://en.wikipedia.org/wiki/Friction

http://en.wikipedia.org/wiki/Mechanical_efficiency

http://en.wikipedia.org/wiki/Split_nut




Design Project

For square threads, Lead = Pitch in single start which is 7 mm, but for double start

thread has a Lead = 2 × Pitch = 2 × 7 mm = 14 mm

dm = 30 – 7/2 = 26.5 mm dr = 30 – P = 23 mm

According to the convention the large composition of the force when be when thesystem would be raised at an inclination. So the equation as per Shigley‟s:

(For raising the load)

( )

12000 N mm = 8863.2 N mm

(For lowering the load)

( )

-12000 N mm -2178.4 N mm

In both cases the resulted torque from the applied is less than the actual torque

applied. Hence proved, it is a self-locking power screw.

Part Name Power Screw

Date Calculated 8-9-11

Calculated by Deepak

Checked by Rajeesh




Design Project

Bolted Joint Design

This bracket is attached to the frame by bolts. This bracket used to hold the lead

screw which functions as push pull mechanism to move lifter and scooter in and out

of the car. Force acting at the centre of the lead screw is considered as 1.7kN which

is half of the calculated total force of 3.4kN. Centre of the force acting is 95 mm awayfrom the base. In general bracket act as a stopper in conjunction with the self locking

lead screw.

25

F F

Pre tension per bolt = Required normal force to provide friction/number of bolts

Assuming between steel to steel




Design Project

Maximum tension in a bolt due to force F (2000N). Assuming the bolts near the force

acting wall will experience maximum tension.

∑

Maximum bolt tension =

Minimum tensile stress area

So grade 4.6, bolt will be ideal (table 8-1 and 8-11 from shigley‟s used for

reference). Where AT is 36.6 mm2.

Bolt need to be checked for shear failure in the case of bolt coming loose.

Tensile stress in same bolt

Assume shear load is carried evenly




Design Project

Definitely

So it is safe to use a grade 4.6, M8

1.25 bolt for this application.

Part Name Bolted Joint


Calculated by Rajeesh

Checked by Christian




Design Project

Welded Joint Design

This bracket is attached to the frame by welding. This bracket fixed opposite side of

the bolted joint explained before. Function of this bracket is same as the bolted joint.

It is assumed that force acting on is half of the calculated total force of 3.4 kN.Maximum stress on the weld only when one direction and in other direction leg of the

bracket will support as well.

Maximum allowable shear stress using E 43 electrode

Neutral axis for the weld pattern




Design Project

Unit second moment of area for the weld (Table 9-2)

Direct shear on the weld

√

Secondary shear from bending about neutral axis

√

√




Design Project

( ) ( )

Maximum allowable shear stress using a E 43 electrode = 129MPa

h=0.2mm. so preferred size for the fillet weld is 3mm

Design factor

Design factor of 14.79 is more than sufficient and weld will be safe.

Part Name Welded joint


Calculated by Rajeesh

Checked by Deepak




Design Project

Lifting Platform Design:

Normal stress = bending stress + axial stress

For this case axial stress = 0

Bending moment:

M= F L =981N x 582.5mm= 571432.5Nmm

Bending stress = Mc/I and I =BH3 /12=600 x 83 /12 =25600mm4

Mc/I= 571432.5mm x 4 mm /256004 = 89.286MPa

Shear stress:

Shear stress= F /A = 981N / (600 x 8) = 0.204 MPa

Equivalent tensile stress = (bending stress2 +3shear stress2) 0.5

= (89.2862+3 x 0.2042)0.5

= 89.286 Mpa

To find out the Sy of the material we have:




Design Project

Equivalent tensile stress < Sy / N

89.286 N < Sy

Thus

Sy > 353.75Mpa

The material we choose is 2014 T6 aluminium, the material has the

following properties:

Sy = 415 Mpa

St = 470 Mpa

P = 2800kg/m3

Total weight of the section is 50.0kg.



Calculated by Peter





Design Project

Pins Design

There are 3 failures modes of the section of connection between the lifting table

and the arms.

F is the total load act on the connection: load act on the lifting table + the weight

of the lifting table, the weight of the lifting table is calculated by Solid Works.

F = load act on the lifting table + the weight of the lifting table = 981 +50 x 9.81 =

1471.5N

Direct shear all 4 pins:

0.6 Sy(pin) /N > F /(2 x 4 x d2 /4)

Then we have Sy(pin) >14.5 MPa

Shear, the connection of the plate:

0.6 Sy(pin) /N > F /((D-d)(t1+t2))

Then we have Sy(pin) > 4.95 MPa

Bearing stress across 4 pins:

0.6 Sy(pin) /N > F /( 4 x d x (t1 +t2))

Then we have Sy(pin) > 0.69Mpa




Design Project

So, final Sy for the pin should be bigger than 14.5 MPa, this is a very small value

for a engineering material, then can easily choose material. The pins on other

side of the arm will not have this much force as these 4 pins, we can use the

same material for them. Then we can choose a cheap material. The material we

choose is the AISI 304, the following is the properties of the material.

Sy = 351 Mpa

St = 420 Mpa

P = 8000kg/m3

Total weight of the section is 0.68 kg



Calculated by Peter





Design Project

Link Design:

F is the total load act on the connection: load act on the lifting table + the weight

of the lifting table + the weight of pins, the weight is calculated by Solid works.

F = load act on the lifting table + the weight of the lifting table = 1769.2 N

When the arms are horizontal to the ground the F makes the biggest moment. In

this situation the arms will receive the biggest bending and shear stress.




Design Project

R‟ = 7971 N

R = 8133.4 KN

288 mm 77.35o

83 mm

484 mm

370 mm

F = 1769.2 N

Cross Section = 2 × 30 mm × 60 mm

F x 370 = R sin (78.2)82.15

F= 1769.2

Then we have:

R = 3133.4 N

R‟=R x sin(78.2)=7971N

I=2BH3 /12= 1080000mm4

C= 30mm




Design Project

SFD

1796.2 N

7971 N

BMD

654.82 Nm

The max moment is at 82.15mm

M(max) =654.82Nm

Bending stress= MC/I=18.20MPa

Shear stress= F/2A= 0.49MPa

Equivalent tensile stress = (bending stress2 +3shear stress2) 0.5 = 18.22Mpa

To find out the Sy of the material we have:

Equivalent tensile stress < Sy / N

Then:

Sy > 65.60Mpa

From the calculation showing, we need a pump power bigger than 8133.4N.

The material we choose is the AISI 304, the following is the properties of the

material.

Sy = 351 Mpa St = 420 Mpa P = 8000kg/m3




Design Project

Material Cost Calculation

PARTS

Volume

(mm3)

Density

(Kg/m3)

Mass

(Kg)

Material Cost

(AUD)

Qty. Net Price

(AUD)

Frame 9147720 2800 25.6 4 1 101.6

Fixture 243248 2800 0.68 4 4 10.9

Link1 356700 8000 2.85 1 2 5.7

Link2 323278 8000 2.58 1 2 5.16

Lifting

Platform

10451952 8000 83.60 1 1 83.6

Pin(HydraulicArm)

98310 8000 0.78 1 1 0.78

Pins(Lifting

Arms)

85893 8000 0.68 1 2 1.36

Bolted Part 698295 2800 1.95 4 1 7.8

Welded Part 769678 2800 2.15 4 1 8.6

Rings(Fixture) 29500 2800 0.083 4 4 1.328

Total material cost = 226.8 = $ 227

Retail Price = 3 × 227 = $ 681

Cost of accessories:

Cost of Hydraulic System = $ 350

Cost of Parallel Tracks (rotary cylinders inclusive) = $ 200

Cost of Split Nut = $ 48.95

Cost of Lead Screw = $ 270

Cost of Installation (System) = $ 150

Total Cost (System) = $ 1699.5




Design Project

Appendix




Design Project

MDP Final Design Report

Documents

Transcript of MDP Final Design Report