Design TipsLatest newsTips-Tricks

Practical Tips on Doubler & Gusset Design

In this tip we review and compare some common doubler and gusset designs in terms of both the geometry and the weld detailing. We also rank them in order of best practise and performance for fatigue life and offer some comments on why this is the case.

Realistic analysis of welded structures takes a lot of expertise; particularly when it comes to fatigue strength. If you would like some peace of mind about some welded components you manufacture, please give us a call; we’ve got the tools and experience to help.

Doubler Design

Here are a couple of options to improve the fatigue strength of doubler plates with simple changes to weld callouts and geometry. To indicate the relative performance of each type a Fatigue Strength Reduction factor is used. The higher the factor, the higher the fatigue strength of the welded joint

Fatigue Strength Reduction Factor

Fatigue Strength Reduction Factor

Weld Detailing
Doubler weld 0Doubler weld 1 (1)
OK – no weld across the end means a sudden change in stiffness between the doubler and section. Weld toe in location of high stress concentrationBETTER – WHY? Smoother transition from the doubler into the section
Geometry Detailing
Doubler weld 1Doubler geometry 2
OKBETTER – WHY? Gradual change in section. No stop/start of weld in location of high stress
Note that the underlying geometry also plays an important part with doubler design; i.e. an optimised doubler on an UB may perform poorly on a RHS box section.


Gusset Design

Weld Detailing
Gusset Weld 1Gusset Weld
OKBETTER – WHY? Weld toe moved away from the sudden change in stiffness
Geometry Detailing
Gusset geometry 1Gusset geometry 2
OK – but there is still a sudden change of stiffness at Point ABETTER – WHY? Modified gusset design gradually distributes stiffness


[All images sourced from: D Radaj and C M Sonsino: Fatigue Assessment of welded joints by local approaches. Woodhead Publishing Ltd. 1998]

Related Posts

Motovated’s Newsletter – October 2018 Message from Greg Hi again. We've changed the newsletter up a bit and so are keen to get your input on how you like it. As usual we've got an interes...
Motovated’s Leon Daly presenting Better by Analysi... Better by Analysis™ with Leon Daly Motovated's Analysis Jedi and General Manager Leon Daly As Motovated's Analysis Manager Leon Daly has been livin...
Additive Manufacturing Process Selection Additive Manufacturing Process Selection SAE International recently announced the release of its first suite of Aerospace Material Specifications (AM...
Hiring Engineers – It’s an art, engineered to a sc... Hiring Engineers – It’s an art, Engineered to a science!Hiring engineers starts with a great job description:Know what you need your engin...
FEA: Static and Dynamic Analysis of Mechanical Par... FEA: Static and Dynamic Analysis of Mechanical Parts The Static and Dynamic analysis of mechanical parts plays a very important role for the efficien...