In Situ Characterization of Damage Development in Cottonid Due to Quasi-Static Tensile Loading

Abstract

Cottonid is a layered material based 100% on cellulose that holds excellent material properties by being completely sustainable. The finite nature of petroleum-based resources nowadays makes these properties significant for technical applications again. To understand how Cottonid reacts to application-oriented mechanical loads and how it fails, development of microstructural damage on the surface and in the volume of Cottonid was studied using innovative in situ testing techniques for the first time. Quasi-static tensile tests were comparatively performed in a scanning electron microscope as well as a microfocus computer tomograph, and the development of defects present in the initial condition of the material was investigated. In the elastic region, no visible damage initiation on the surface and a decrease of overall void volume within the gauge length could be detected. When reaching the yield strength, crack initiation on the surface starts at critical areas, like pores and microcracks, which propagation and assembly could be visualized via scanning electron micrographs. In the plastic region, an increase in void volume could be shown in the gauge length until final failure of the specimen. Innovative material testing techniques presented in this study support lifetime estimation in technical applications and understanding of process–structure–property relations. Particularly, characterization of microstructural damage development due to a mechanical load, which leads to final failure of the specimen, is essential to be able to create material models for lifetime prediction in respect to variable manufacturing or application parameters.

Impact of solar radiation on chemical structure and micromechanical properties of cellulose-based humidity-sensing material Cottonid

“…Furthermore, the impact of outdoor weathering conditions on the long-term actuation and fatigue behavior is characterized. The aim is to structurally optimize Cottonid [37] through adjustment of the manufacturing process for the production of Cottonid elements with tailor-made properties for either adaptive or constructive applications.…”

Impact of Solar Radiation on Chemical Structure and Micromechanical Properties of Cellulose-Based Humidity-Sensing Material Cottonid

“…Furthermore, the impact of outdoor weathering conditions on the long-term actuation and fatigue behavior is characterized. The aim is to structurally optimize Cottonid [35] through adjustment of the manufacturing process for the production of Cottonid elements with tailor-made properties for either adaptive or constructive applications.…”

Constant Temperature Approach for the Assessment of Injection Molding Parameter Influence on the Fatigue Behavior of Short Glass Fiber Reinforced Polyamide 6

“…Further improvement is possible by extending µCT with in situ testing. By using this technique, it is possible to execute µCT recordings at applied load to identify damage mechanisms [ 46 ] without crack closure effects. In combination with fatigue testing, sequential or intermittent tests can be conducted, and the material state recorded to establish an understanding regarding damage initiation and propagation occurring in the material inner.…”

“…With the use of digital volume correlation (DVC), deformation and strain in the material inner can be analyzed and correlated to the damage state recorded through µCT, extending the possibilities even further. In this regard, relaxation and creep of the material need to be taken into account, since µCT scans can take several hours and therefore lead to a blurred image and inaccurate representation of the material state [ 45 , 46 ].…”