PSI - Issue 61

Necdet Ali Özdür et al. / Procedia Structural Integrity 61 (2024) 277–284 N.A. O¨ zdu¨r et al. / Structural Integrity Procedia 00 (2024) 000–000

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2. Materials and Methods

2.1. Setup

The experimental setup that is used in deformation and temperature measurements is shown in Fig.1(a). The major component of the experiment, a FLIR A655sc thermal camera equipped with 1.5X close-up IR lens is shown in here with the label 2 . The IR camera is set to record at 640x240 pixel resolution at 100 Hz. It is pointing towards a Kammrath & Weiss 10 kN tension-compression module (labeled 4 ), which is placed on top of a Newport XYZ positioning stage ( 5 ). The stage is used to carry the tension-compression module under the macro-DIC line ( 3 ),which consists of a 1X Edmund Optics zoom inspection microscope (further details in Erman et al. (2023)). The entire setup rests on a vibration isolation table ( 7 ), and is covered with an opaque curtain ( 8 ) to block outside light. Here, all infrared thermography (IRT) measurements with in situ loading are conducted in dark conditions. The micro-DIC camera labeled as 1 is not utilized for this experiment. The dog-bone Mg AZ31 sample is wire-EDM cut from a hot-rolled plate (the same saw material in Erman et al. (2023)) as depicted in Fig. 1(b), so that the rolling direction of the plate coincides the loading axis of the specimen. The HCP unit cell in the same figure also illustrates an abundant orientation observed in rolling texture. The sharp rolling texture of the plate can be seen in the pole figure provided in Fig. 1(d). When compressed along the rolling direction, this type of sharp texture is known to trigger profuse and coordinated activity of { 101¯ 2 }⟨ 1¯ 011 ⟩ tensile twins. To serve as a reference temperature measurement surface, a leftover Mg part is glued to the side of the grip section, with a piece of bakelite in between to act as a thermal insulator. The ensemble of the dog-bone specimen and the stress-free side attachment is sketched in Fig. 1(c). Both surfaces are spray painted matte black for increased surface emissivity. Prior to the experiment, a reference image of the initial specimen surface is captured with the macro-DIC line using external light source (label 9 in Fig. 1). Then the specimen is carried under the thermal camera and the light is turned o ff . The dark conditions are necessary for the thermal measurements but preclude the recording of any other macro-DIC images. Under the IR camera, the dog-bone sample is compressed continuously for 16 seconds with the maximum possible displacement rate the tension-compression module is capable of (20 µ m / s). The IR signal emitted by the specimen (and the dummy sample) is recorded with the thermal camera during loading (and for a brief period 2.2. Sample 2.3. Experimental Procedure

Fig. 2. (a) IR image and; (b) macroscopic image with DIC regions of interest marked with rectangles; (c) comparison of IR-DIC and macro-DIC measurements.