Process Of Composite Parts Research Articles

Material characterization of cyanate ester material for structures with high dimensional stability requirements

The degradation temperature, cure kinetics, viscosity, shrinkage, thermal expansion, and the modulus of RS-36-1 (modified epoxy), RS-3C and RS-3 (cyanate esters) are measured to evaluate the dimensional stability of these materials. L-shape carbon fibre-reinforced laminates with these polymer matrices are manufactured using Out-of-Autoclave (OoA) Vacuum Bag Only (VBO) processing and the spring-in angle is measured. Upon heating, cyanate ester resins experience expansion followed by shrinkage, which brings the overall shrinkage close to zero. Their coefficient of thermal expansion is found to be lower in comparison to the epoxy material, showing the lowest amount of spring-in. Finite Element simulation using COMPRO CCA is performed and the results are compared to the measurements performed on L-shape laminates. The methodology described herein shows phenomenological insight on the cyanate ester materials and the possibility to predict the effect of residual stresses during processing of composite parts, demonstrating high dimensional stability of cyanate esters.

Albi II – a new generation development

The UL-39 Albi university's all-composite ultralight aircraft project, powered by a piston engine and ducted fan, continues at the Department of Aerospace Engineering at Faculty of Mechanical Engineering CTU in Prague and its partners ZALL JIHLAVAN airplanes, s.r.o. and LA composite, s.r.o. by developing its new generation. The article is a follow-up to a contribution from 2017, where the entire genesis of the first prototype was described. The introduction summarizes the experience of the prototype operation and analyzes the deficiencies that required a major redesign of the propulsion unit. Aspects leading to the choice of another propulsion unit arrangement and changes in the ducted fan, airframe and systems are described. The fuselage of the airplane has undergone a dominant change. The paper describes not only structural changes leading to the reduction of the width of the fuselage and its wetted area, but also the changes in manufacturing process of composite parts leading to weight reduction. Following the changes in the fuselage design modifications of the wing (mainly high lift devices) and modification of the horizontal tail plane are described. At the end there is a plan of further development described, which should ultimately lead to the commercialization of the project.

Key factors affecting permeability measurement in the vacuum infusion molding process

AbstractThe composites industry, under increased environmental constraints, is seeking to shift from existing open mold manufacturing processes for composite parts. A promising manufacturing technology known as the vacuum infusion molding process is gaining acceptance among composite‐parts manufacturers since it involves low tooling cost and allows complete elimination of volatile organic compounds (VOC). The process is similar to the resin transfer molding process; however, in the vacuum infusion technique, a polymeric film, often referred to as vacuum bag, replaces the stiff mold cover. The film is sealed against the lower half of the mold, at the periphery. Air expelled from the mold cavity results in the compaction of the reinforcement by the atmospheric pressure present on the outer side of the polymeric film. Finally, resin impregnates the mold cavity, usually through a resin distribution channel. The process is mainly developed for large‐scale structures, where material cost is an important parameter and users cannot afford any production pitfalls. Among process parameters that affect resin flow in the vacuum infusion molding process is the permeability of the reinforcement stack, which has to be measured and evaluated taking into consideration the requirements of the process. A possible approach is the definition of a parameter that defines the maximum infused length, and this parameter will take into account the structure of the reinforcement, the resin viscosity, the fiber volume fraction and inlet geometry.

Resin/resin Bonding Strength and Control of Interface Geometry in Simultaneous Composite Injection Molding

A simultaneous composite injection molding (SCI. molding) process has been developed based on a conventional two color injection molding process. This is a new process of composite parts in which two different melts are injected into one mold cavity simultaneously through two channels. It has outstanding advantages of high resin/resin bonding strength and low production cost compared with the conventional method.In the present paper, the resin/resin bonding strengths of ABS/ABS, PBT/PBT and ABS/PBT composite molding produced by SCI. molding are compared with those from the conventional injection molding. The optimum control methodologies of the interface geometry are discussed.