Damage mechanics Fatigue lifetime FEA and Fatigue damage calculation. Geometry Material property Damage evolution law

Mean load change – Prediction models Linear Cycle Mix (LCM) effect Two constants need to be defined Constants change with the type of load spectrum N [cycles to failure] Residual load ‘R’ [kN] Fatigue load decreasing a b c d e No interaction effect considered Interaction effect considered Complex loading

Vertical jump approach Independent of type of load spectrum No constants need to be defined Can be applied to any type of interaction effects N [cycles to failure] Residual load ‘R’ [kN] Fatigue load decreasing a b c d No interaction effect considered Interaction effect considered Complex loading

Variable amplitude fatigue Type of load interaction Experimental results (No. of cycles) Miner rule prediction (No. of cycles) LCM approach (No. of cycles) Vertical jump approach (No. of cycles) L1 = 6.5kN; L2 = 8kN n1=10; n2= L1 = 6.5kN; L2 = 8kN n1=1000; n2= L1 = 8kN; L2 = 9.5kN n1=10; n2= L1 = 8kN; L2 = 6.5kN n1 = 10; n2= Results and discussion

AC DC against CAA surface pre-treatment Static strength Cycles to failure for max. fatigue load of 60% of static strength

ACDC Summary  A two-stage anodisation process has been developed to facilitate interphase formation without compromising corrosion protection.  The process is simple, fast and robust.  Initial results show excellent adhesion and corrosion performance – comparable to CAA.

4. CONCLUDING REMARKS  Given an understanding of film formation mechanisms oxides can be nanoengineered for optimised adhesion.  Hexavalent chromium chemistry is widely used in Al processing within the aerospace, defence, automotive sectors. Drop-in replacements are urgently sought.  ACDC processes offer additional advantages: environmentally benign simple increased processing speeds.