Lumen maintenance prediction for LEDs: New insights

Commercial claims for LED-based products in terms of lumen maintenance are fully based on TM-21 extrapolations using LM-80 data. We presented an approach based on statistical data analytics, following the work from Yu & Tseng, at EuroSimE2015. Since then, more LM80 test data came available both for High Power (HP) and Mid Power (MP) LEDs....

Constant-amplitude and flight-simulation fatigue tests on adhesive bonded lap joint specimens of 2024-T3 sheet material

Fatigue tests were carried out on Redux and FM 123/5 bonded specimens at various stress levels, temperatures (RT to 65 C) and low and high test frequencies. Observations were made on the type of failure (bond line failure or sheet failure) and the significance of the adhesive squeezeout for crack nucleation. An analysis of the data and a...

Some tests to assess the effect of crack stoppers on the fatigue life of centre-notched sheetspecimens

Several simple crack stopping methods were evaluated In fatigue crack propagation tests on 2024-T3 Alclad sheet specimens. After precracklng until a crack of 40 mm was obtained crack stoppers were Installed and the fatigue test was continued. Crack stoppers Installed In stop holes were: a blind rivet, a hard driven rivet, a heavily tightened...

Effect of an anti-corrosion penetrant on the fatigue life in flight-simulation tests on various riveted joints

Comparative flight-simulation tests on four types of joints of 2024- T3 sheet material were carried out with and without application of the penetrant LPS-3. Types of joints were douhle strap joint with hi-lok bolts, asymmetric strap joint, lap joint with countersunk rivets and lap joint with dimpled holes. Observations on slip during the fatigue...

Environmental effects on crack grwoth in flight-simulation tests on 2024-T3 and 7075-T6 material Supplement: Compilation of test data from an investigation on the effect of environment on crack growth under flight-simulation loading

Flight-simulation tests based on a standardized gust load spectrum were carried out in normal air, very dry air and salt water. Specimen thicknesses were t = 2 mm and t = 10 mm, mean stress in flight was 70 or 55 MN/m². In all cases a significant effect of the environment was found. Fatigue lives for t = 10 ram were much shorter than for t = 2...

Flight-simulation tests on notched elements

Tests were carried out on open-hole specimens, lugs and riveted strap joints of 2024-T3 and 7075-T6 materials. The effects of design stress level, truncating high-amplitude gust loads and omitting low-amplitude gust cycles were stuaied. Observations of the open-hole specimens include data on crack initiation, crack closure and damage increments....