Reliable durability assessment of welded yellow goods equipment

• Main Author: Flynn, Dean
• Published: Swansea University 2010
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.752219

Weld fatigue performance is a main design consideration with Yellow Goods vehicles and can determine the overall product durability. Accurate fatigue life prediction is critical but current durability assessment involves extensive testing. This design process lacks efficiency and presents scope for a finite element (FE) based weld fatigue assessment method. Used early in the design stage, this method will improve time-to-market of products and achieve robust 'right-first-time' designs. Research work has been carried out into applying the 'Master S-N Curve' approach to thick-plate construction and agricultural equipment. Weld fatigue data was generated on a range of simple welded coupons and converted for the fatigue life prediction of welded structures using the structural stress damage parameter. Overall, a single Master S-N curve was achievable for a range of different weld joint configurations. The method achieved good condensation of the geometry dependent load-life fatigue curves into a single structural stress against life curve. The structural stress method was further extended to fatigue lives of weld throat failures with good condensation of the data. Excellent correlations were achieved between solid and shell element models. The concept proved to be effective and largely insensitive to FE mesh type and size. However, limitations were found with shell element models when predicting weld throat failures. The structural stress measurement technique was employed and a master curve generated, derived from coupon strain-gauge recordings. The Master S-N curve approach was applied in the fatigue assessment of a laboratory test component and production component for the construction industry with limited success. Predictions were compared with recorded values from component fatigue tests. More accurate predictions and improved correlations were found when using separate failure mode master curves. Overall the work showed some potential for the use of the Master S-N Curve approach in the early design stage of construction and agricultural welded structures.