Ultrasonic fatigue of unfilled and carbon nanotube (CNT) reinforced polyetheretherketone (PEEK).

Fatigue properties of polyetheretherketone (PEEK) and multiwall carbon nanotube (CNT) reinforced PEEK were investigated with the ultrasonic fatigue testing method. Lifetimes were measured in the high and very high cycle fatigue regime at resonance frequency 19 kHz and load ratio R = -1. Pulse-pause loading served to avoid specimen self-heating and led to effective cycling frequencies in the range from several hundred Hz to about two kHz.

Ultrasonic fatigue testing of concrete.

Cyclic compression fatigue properties of concrete are studied with the ultrasonic fatigue testing method with cycling frequency 19 kHz and are compared to servo-hydraulic tests performed at 60 Hz. Ultrasonic testing was found applicable for rapid generation of very high cycle fatigue (VHCF) data of concrete. Fatigue cracks can be initiated, however specimens do not rupture, since cyclic stresses decrease with increase of compliance in displacement controlled ultrasonic tests.

Usability of Ultrasonic Frequency Testing for Rapid Generation of High and Very High Cycle Fatigue Data.

Ultrasonic fatigue testing is an increasingly used method to study the high cycle fatigue (HCF) and very high cycle fatigue (VHCF) properties of materials. Specimens are cycled at an ultrasonic frequency, which leads to a drastic reduction of testing times. This work focused on summarising the current understanding, based on literature data and original work, whether and how fatigue properties measured with ultrasonic and conventional equipment are comparable.

Insight into the nanostructure of anisotropic cellulose aerogels upon compression.

Cellulose II aerogels are a highly porous class of biobased ultra-light-weight materials. They consist of interlinked networks of loosely aggregated cellulose fibrils. The latter typically have random orientation due to spontaneous phase separation triggered by addition of antisolvent to moleculardisperse cellulose solutions.