Impact of nanoparticles on the process‐induced distortions of carbon fiber reinforced plastics: An experimental and simulative approach

Abstract

This article investigates the potential of aluminum oxide nanoparticles for the reduction of process-induced distortions of carbon fiber reinforced plastics (CFRP). Therefore the matrix properties, which affect the distortions, are experimentally and mechanistically analyzed in detail at various particle contents. The results clearly show an increasing impact of raised particle content on gelation, chemical and thermal shrinkage, on Young's modulus, as well as on Poisson's ratio. These alterations can be successfully transferred to reduce spring-in of L-shaped CFRP brackets, which are manufactured by infusion technology. However, it is found that particle contents higher than 5 wt % are needed to influence these parameters. For further understanding of the parameters controlling spring-in, a numerical sensitivity analysis is performed by the correlation of various matrix parameters and the induced distortions. The results from a structural simulation reveal that changes in thermal and chemical shrinkage as well as in gelation have a major impact on the distortions, but the modes of action of the particles also have to be taken into consideration. These mechanistical insights about nanoparticle impacts might be a valuable approach to lower or overcome distortions in composite materials in the future.

Subsurface Stress Measurement in GIS Epoxy Composite by Using LCR Waves

“…When the LCR method is applied, the relationship between the propagation time T and the internal stress σ, is shown in Equation ( 2) [14]. Dos Santos et al used Equation (2) to investigate the relationship between uniaxial tensile internal stress and LCR propagation time in carbon fiber composites with epoxy matrix [14]:…”

“…In order to obtain the calculated internal stress σ c , the internal stress variation dσ = σ − σ 0 and the propagation time variation dT = T − T 0 are substituted into the Equation (2). The calculation equation of σ c is shown as:…”

“…The basin insulators are manufactured by thoroughly mixing epoxy resin, alumina filler, and a curing agent in certain proportions, followed by pouring and curing processes. During their manufacturing, internal stress is caused from unevenly stirring raw materials, shrinking chemicals caused by polymerization reaction (i.e., liquid state to the solid state) [2], shrinking thermal while cooling down to room temperature [2], and large particle precipitation. Additionally, internal stress is induced from transportation friction and vibration.…”

Modeling Spring-In of L-Shaped Structural Profiles Pultruded at Different Pulling Speeds

“…Three methods were used to measure the chemical shrinkage—by bi-material strip, by Thermal Mechanical Analysis, and by FBG sensors—with the latter producing the most reliable results. Exner et al [ 78 ] have shown experimentally that the addition of aluminum oxide nanoparticles in the amount of at least 5 wt % reduces chemical and thermal shrinkage, resulting in a reduction of spring-in in vacuum-infused CFRP L-shaped composites. In 2019, Groh et al [ 79 ] in the experimental study of RTM-fabricated L-shaped CFRP composites based on Fast Curing Epoxy Resin have shown the absence of relation between the spring-in and the cooling rate.…”

An Ultrasonic Longitudinal Through-Transmission Method to Measure the Compressive Internal Stress in Epoxy Composite Specimens of Gas-Insulated Metal-Enclosed Switchgear

“…Internal stress can be generated in basin insulators, during their manufacture, transportation, installation, and operation. In the manufacturing process, residual stress is caused by chemical shrinkage due to cross-link reactions and thermal shrinkage while cooling down from curing to room temperature [4]. In addition, internal stress results from the vibration and friction in the transportation; the mechanical force due to unbalanced installation and switching operations; the vibration induced by short-circuit electrodynamic force; the thermal gradient stress due to central conductor operating heating and the different thermal expansion coefficients between the epoxy composite and insert metal in the operation.…”