Ehret, A.

Kunkel, J.

Schwab, S.

Voss, B.

Weinert, J.

GSI Repository

Optimizing the manufacturing method of detector parts ∗J. Kunkel1, A. Ehret1,2, S. Schwab1, J. Weinert1, B. Voss1, for the PANDA collaboration , and theFAIR@GSI RBDL11GSI, Darmstadt, Germany; 2University of Applied Sciences, Darmstadt, GermanyFor the Forward GEM-Tracker of the PANDA experi-ment at FAIR [1, 2], as part of structural elements of the socalled GEM-Disc detectors, rings with high dimensionalstability and optimized material budget need to be pro-duced. The parts are up to 1.5 m in diameter, 8 mm widthand only 0.5 mm thick. They need to withstand forcesof up to 15 N cm-1 in radial direction. Parts made fromconductive material as well as highly isolating ones are re-quired. Industrial products with the appropriate features arenot available and thus the process was set up and optimizedat GSI.Finite Element Method (FEM) simulations (see figure 1)were done precedent to manufacturing sample parts. Theresults of these calculations show the necessity of uniformmaterial properties in direction of the load. This can beachieved by compounds with specific material orientation.Composite materials of carbon fibre and resin have excel-lent properties in elastic modulus and tensile strength, andare electrically conductive. Compounds of glass fibre arenon conductive but have a lower elastic modulus. Currentlyfibres made from basalt are under test which offer interme-diate properties. They are non conductive, stiffer than glassfibres and commercially available at moderate prices.Figure 1: Left: FEM simulation is used to estimate the de-formation of the part. Right: small test parts of basalt andglass fibres.To achieve a uniform fibre orientation in the rings ap-propriate for the orientation of the radial loads they shouldwithstand, a winding apparatus (see figure 2) has been buildwhere the fibres are wound up to a spool. The windingmotion is achieved by rotating the spool around its axis.A motor/gear/brake combination applies a constant trac-tive force on the roving (a bundle of fibres) which allowsa controlled stacking of the fibres without larger flaws andwith the desired high amount of fibre content (>60 %) in∗Work supported by FAIR@GSI PSP code: 1.4.1.order to maximize the stability and minimize the materialbudget. Several types of resin have been used in the tests,the final choice will be made taking into account the needfor ageing-free operation of the detectors. The winding ismade up to a larger outer diameter of the ring than neces-sary. The excess material is later removed by milling. Alsothe connection to the centre bar and additional geometry(holes, chamfers, fillets etc.) are milled.Figure 2: The devices to wind the rings with variable size,thickness and fibre content. The roving comes from theright, goes through a impregnating bath, and is kept on aconstant force by a controlled brake before it is wound tothe spool (shown on the left).After producing parts of different material combinationtest for mechanical, chemical and physical properties willbe performed together with the collaborating universities.Based on this tests both material and geometry will be op-timized. By comparing the FEM results with the actualbehaviour of the parts the simulation settings will be opti-mized. This will be very helpful for the simulation of otherdetector parts made of composite material.References[1] B. Voss, D. Auer, A. Ehret, C. Kaya, J. Kunkel, A. Neeb,A. Remers, J. Reuss, S. Schu¨tz, Ed. Traut, El. Traut, E.T.Yamedji, The mechanical structures of the PANDA GEM-Tracker, GSI Scientific Report 2011, GSI Report 2012-1,2012, p. 123[2] B. Voss, J. Kunkel, R. Karabowicz, The GEM-Discs for thePANDA experiment, GSI Scientific Report 2010, GSI Report2011-1, 2011, p. 338FG-S-FRS-09 GSI SCIENTIFIC REPORT 2013344 doi:10.15120/GR-2014-1-FG-S-FRS-09

Optimizing the manufacturing method of detector parts

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Optimizing the manufacturing method of detector parts

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