“Fix Forever, Not Forever Fixing”

Understanding design and repair concepts is essential tomaximising safety and minimising running costs of plant andequipment. Making Metal Work is a 4 day training course focusedon structural failures and repairs, including the following topics:

• Risk and Factors of Safety• Loads and Load Path• Material Properties• Types of Applied Loads• Stress Concentrations and Stress Flow• Fatigue of Welds and Bolted Joints• Techniques for Improving Life of Repairs• Importance of Welding Parameters• Failure Analysis / Fracture Morphology• Non Destructive Testing• Case Studies

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

Risk and Factor of Safety

LOAD INCREASESOperator behaviour,inclination, impact,storms wind, ice etc

STRENGTH DECREASESFatigue cracking, wear, sundamage, insects, corrosion,erosion etc

“ACCIDENTS OCCUR WHEN EVERYTHING IS FINEUNTIL SUDDENLY IT ISN’T”

Concept of loading vs design strength and how both of thesecan determine whether a structure is safe or not: the load canincrease for various reasons and the strength/structuralcapacity can decrease over time or instantaneously.Separation of these curves is the factor of safety.

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

Loads and Load Path

How are loads transferred through a machine:bending, compression, tension etc

300mm 1800 mm

W

F

15t

A

15 tonne

200 mm 300 mm

1800 mm

W

FA

Importance of understanding how load is carried in acomponent or structure, the type of loading and the resultingstresses. Basic stress calculations, moments and forceequilibrium.

Find forces at W and F fora 15t cylinder force

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

Material Properties

• Strength (yield and ultimate),toughness, modulus (stiffness)

Stress-strain curve, elastic modulus, stiffness, toughnessand effect on critical crack length. Triangle of integrity. Heattreatment, quench and tempering and transformation todifferent microstructures.

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

• Load distribution

• Moments - Bending and torsion

• Buckling

Types of Applied Loads

Static and dynamic loads. Point loads and uniformlydistributed loads. Moments causing bending and torsion.Buckling.

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

Stress Flow andConcentrations

• Use of polariscope

• Stress concentrations

Stress flow and stress concentrations. Demonstrated withuse of a polariscope. Effect of holes, weld toe geometry,sharp notches, partial penetration in welds, neutral axis.

FF

A

FF

A

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

Fatigue of Welds• Effect of welding on fatigue life

Why welds fail infatigue. Use of AS4100fatigue curves andunderstanding differentclasses of weld.

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

Improving the Life of Welds

Techniques forimproving weldfatigue life dealingwith stress range,geometry andtreatment of the weldtoe.

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

Important WeldingParameters

• Pre-heat to reduce cold cracking,effect of hydrogen

• PWHT to reduce residual stresses

• Appreciation of alloy content andcarbon equivalent

Details on weld consumable classification and the number ofparameters that can be varied. Value of preheat andcalculation of the carbon equivalent. PWHT and the effectsof residual stress in failures. Introduction to AS 1554 anddiscussion on GP, SP and FP welds.

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

Fracture Morphology

Identification of failures: characteristics of fracture surfaces –brittle, ductile, fatigue, torsion, bending (rotating andalternating) tensile, buckling etc.Physical samples will be available for inspection and discussion.

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

Non Destructive Testing

Description of various NDT methods available and theadvantages and disadvantages. Experience with their efficacyin various case studies is described.

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

Failure Case Studies

• Reclaimer collapse

• Dragline boom failures

• Hyatt walkway failure

• Minneapolis bridgecollapse

• Comet aircraft

• Haul truck chassiscracking

• Torsion failures in shafts

• Aluminium box trailer

Numerous case studies are discussed through the course toillustrate all the aspects of structural failure and repairs. Theseare taken from personal experience as well as a few welldocumented classic cases in the public domain.

• Drum brittle fracture

• Shovel fatigue

• High pressure pipe branch

• Axle welding

• Weld failures – wrongconsumables

• Weld failures – no preheat

• Elution column GRP

• Casting defects and failure

• Bucket cracking and repair

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

Course Materials• Numerous models are used to illustrate the

concepts described, including:– Polariscope for visualisation of stress concentration

– Bolting model for how preload affects cyclic loading

– Buckling jig to demonstrate various end constraints

– Models for neutral axis, bending, shear and torsion

– Model to illustrate shear centre and the correctplacement of reinforcement and

– Fractured components are used to show differentfailure modes

• Assessments are done after each section ofwork with a combination of multiple choiceand calculation type questions. These areworked through with the class in a tutorialstyle before moving to the next section.

• Each participant is provided with a 2nd Editioncopy of the book “Metal Where It Matters” aswell as copies of the slides used in theclasses.

CMP ENGINEERSMECHANICAL ENGINEERING CONSULTANTS

CMP ENGINEERS PTY LTD

PO BOX 247, SPRING HILL, BRISBANE, Q. 4004

2ND FLOOR,457 UPPER EDWARD ST

T 07 3839 2045 F 07 3832 3491

email@cmpeng.com.au

Turnkey SolutionsLoadquip is the manufacturing arm of CMP Engineerswhich supplies products nationally and internationallyfor mining and heavy industry. Through Loadquip, CMP Engineers can offer turnkeysolutions, completing projects from initial specificationthrough fabrication, to on-site commisioning.

email@loadquip.com.au

www.loadquip.com.au

www.cmpeng.com.au