Welded Joints Part 1 || Machine Design

 

Introduction  : 

It is a type of joint which is a Permanent type.

Welded joint can be obtained by the fusion process ,Fusion of the Edges of the two work part or work piece to be join together with or without under the Application of Pressure and filler material.

Advantages 

• It takes less time as compared to that of riveted joint

• It can be weld any part of structure at any point but in case of Riveting there is enough clearance requires

• It has a great Strength as compared to that of riveted joint

• Structure of welded appears smooth so that is looks pleasing

• It can provides Maximum Efficiency which can be 100% But in the case of Riveting it in not possible

• Riveted structure is more heavy but Welded structure is lighter

Disadvantages 

• Highly Experienced and Skilled Labour Required

• Inspection work is more  difficult than Riveting

• Due to heat may there additional stress generates or develope

• Since there is no any kind of provision is kept for Expansion as well as Contraction in the frame so hogh chance of Cracking 

# The process of Weldo g broadly classified into two categories

1. Fusion Welding
2. Forge Welding 

Note:- 

The process of Fusion Welding can be classified in to follow groups

1. Thermit Welding
2. Gas Welding
3. Electric Arc welding 

Types of Welded Joints

Lap Joint or Filler Joint 

✔️ the lap joint is formed when 2 parts are placed one over another and then weld

✔️ It may be one Side or Double Sides

✔️ This types of Welding joints are mostly use to join two lieces with different Thickness 

But Joint

# The lap joint or Filler joint is subdivided into two parts

Parallel Fillet

• Welding is done parallel to the line of action of load

Transverse Fillet

It can also be classified into 2 categories

1) single transverse 

• Welding is done one side which is perpendicular to the line of action of load.

2) Double Transverse 

• Welding is done two sides which are perpendicular to the line of action of load.

Notes :-

Total Length of Weld = Length of Weld + Weld Run

i.e

L = l + 12.5

# Some types of Butt Joints

How to calculate Strength of Fillet Lap Joint?

How to Calculate Strength of Fillet Lap Joint ?

#Notes :-

• Transverse fillet failures at angle 67.5°

• t=0.707S , Where t is Thickness of throat and S is Size of weld

• In transverse fillet weld Joint , the size of Weld is Equal to 0.707 X Throat of weld

• Combined weld= Transverse + Fillet

• Transverse Fillet Strength > Parallel Fillet Weld

• For Design always Minimum Strength Required

• For a Parallel load on a fillet weld of equal leg ,The plane of Maximum Shear occurs at 45°

For Designing

• Single Transverse , Strength= 0.707 (σt)*S*L

• Double Transverse, Strength=2*0.707 (σt)*S*L

Welding joint part 2

Numerical Section 

[Q.1]

A plate 200 mm wide and 15mm thick is to be welded to another plate by means of double parallel fillets.The plates are submerged to a static load of 80kN. Find the length of weld if the permissible shear stress in the weld does not Exceed 65MPa

[Q.2] Try yourself 

A plate 300 mm wide and 18mm thick is to be welded to another plate by means of double parallel fillets.The plates are submerged to a static load of 80kN. Find the length of weld if the permissible shear stress in the weld does not Exceed 60MPa

Ans :- 52.4mm (without weld run)

64.9mm( with weld run)

TOPICS :

Special Cases

Ultrasonic Welding Process 

Thanks