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Stress Measure Device

IP.com Disclosure Number: IPCOM000249604D
Publication Date: 2017-Mar-07
Document File: 2 page(s) / 103K

Publishing Venue

The IP.com Prior Art Database

Abstract

During the fiber metal laminat (= FML) manufacturing flat aluminium sheets (thickness 0.4mm) to be lay down into the manufacturing mould with double curvature. This causes internal stresses in the sheets due to properties of the material and adversely influences the manufacturing process and also stresses and fatigue properties of the laminate after bonding process. The calculation of the internal stresses can be performed both theoretically, and also based on manufacturing trials, but cannot be predicted absolute exact. For FML design is very important to know the internal stresses. This gives the possibility to perform correct stress and fatigue calculation of the FML part. A measurement sheet is suggested giving the possibility to measure the internal stresses based on existing manufacturing mould. After calibration, exact measures and internal stress prediction should be possible.

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1. ABSTRACT

During the fiber metal laminat (= FML) manufacturing flat aluminium sheets (thickness 0.4mm) to be lay down into the manufacturing mould with double curvature. This causes internal stresses in the sheets due to properties of the material and adversely influences the manufacturing process and also stresses and fatigue properties of the laminate after bonding process. The calculation of the internal stresses can be performed both theoretically, and also based on manufacturing trials, but cannot be predicted absolute exact. For FML design is very important to know the internal stresses. This gives the possibility to perform correct stress and fatigue calculation of the FML part. A measurement sheet is suggested giving the possibility to measure the internal stresses based on existing manufacturing mould. After calibration, exact measures and internal stress prediction should be possible. 2. DISCLOSURE

The measurement sheet contents of a thin aluminium sheet (t=0.4mm) size e.g. 1000 x 1000mm. Dimension can be flexible due to the size of the mould to be measured. Equipped with several strain gauges bonded on the sheet in equivalent distances. The distance can be defined case by case. Stresses in Alu-sheet in flat condition are to be zero. The calibration of the measuring devices and strain gauges to be performed in such way that all the indication are zero (see Fig. 1 and Fig. 2). The device can be placed into the mould to be measured (see Fig. 3). The measured stress...