BALU: Largest autoclave research facility in the world

Among the large-scale facilities operated at the Center for Lightweight-Production-Technology of the German Aerospace Center in Stade BALU is the world’s largest research autoclave. With a loading length of 20m and a loading diameter of 5.8 m the main objective of the facility is the optimization of the curing process operated by components made of carbon ber on an industrial scale. For this reason, a novel dynamic autoclaving control has been developed that is characterized by peripheral devices to expend the performance of the facility for di erential applications, by sensing systems to detect the component state throughout the curing process and by a feedback system, which is capable to intervene into the running autoclave process. *Cite article as: DLR-FA & DLR-ZLP. (2016). BALU: Largest autoclave research facility in the world. Journal of large-scale research facilities, 2, A57. http://dx.doi.org/10.17815/jlsrf-2-94

Abstract: Among the large-scale facilities operated at the Center for Lightweight-Production-Technology of the German Aerospace Center in Stade BALU is the world's largest research autoclave.With a loading length of 20m and a loading diameter of 5.8 m the main objective of the facility is the optimization of the curing process operated by components made of carbon ber on an industrial scale.For this reason, a novel dynamic autoclaving control has been developed that is characterized by peripheral devices to expend the performance of the facility for di erential applications, by sensing systems to detect the component state throughout the curing process and by a feedback system, which is capable to intervene into the running autoclave process.

Introduction
For the manufacturing of advanced and large scale composites autoclave devices are preferable or even imperative to assure achieving the high demands of quality especially in the aviation industry.It is for this reason, the autoclave process is in urgent need of higher productivity, exibility, low part costs and low scrap rate.
The current research deals with a new concept for autoclave process control which is currently developed.The concept is based on sensors obtaining quality relevant process parameters and a real time process simulation able to predict multiple scenarios of di erent control strategies.The so called MAS-TERBOX is the center piece of this new process control concept.It serves as interface between sensors including data acquisition, the process simulation and the real autoclave and takes decisions for the process control based on sensor data, simulation results and data bases.This intelligent process control will be able to react to process and product deviations leading to an enormous reduction of scrap parts.Also as the process is controlled directly in function of the product's quality development, the process time can be reduced dramatically.Due to the fact that the quality assurance is performed online during the process, the inline or o ine part inspection could be reduced as well.

BALU -The research autoclave
The basis for the speci cation of the required parameters of BALU is based on current and future manufacturing tasks.Regarding these tasks the research autoclave has the following dimensions and operating parameters: • Loading length, diameters, weight: 20m, 5.8m, max.100t of invar (FeNi36) • Power requirements: 3.8MW • Temperature and pressure range: 420°C, 10 bar For the manufacture of ber composite components in autoclaves a pressure up to 10bar are needed.
The appropriate medium is provided with the help of various system components.This is due to the integration of a plant for generating nitrogen in a compressed air system.There are two reservoir pressure containers available for the inert gas supply to the autoclave with a capacity of 200 m 3 .The pressure inside the containers of 32 bar allows a total volume of 12800 m 3 nitrogen.Other sensing systems • Ultrasonic and dielectric measuring systems to monitor the curing process (resin ow, laminate thickness) • Thermographic system for global temperature measurement, leakage detection in vacuum housings etc. • Resin ow and mixing ration measurement in infusion processes with special and optical sensing systems , Zentrum für Leichtbauproduktionstechnologie (ZLP), Deutsches Zentrum für Luft-und Raumfahrt e.V. (DLR), phone: +49 531 295-3709, email: Hakan.Ucan@dlr.de-Dr.-Ing.Felix Kruse, Zentrum für Leichtbauproduktionstechnologie (ZLP), Deutsches Zentrum für Luft-und Raumfahrt e.V. (DLR), phone: +49 531 295-3700, email: Felix.Kruse@dlr.de-Prof.Dr.-Ing.Martin Wiedemann, Institut für Faserverbundleichtbau und Adaptronik (FA), Deutsches Zentrum für Luft-und Raumfahrt e.V. (DLR), phone: +49 531 295-2300, email: Martin.Wiedemann@dlr.de