PSI - Issue 53

Reza Ahmadi et al. / Procedia Structural Integrity 53 (2024) 97–111 Author name / Structural Integrity Procedia 00 (2019) 000–000

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of temperatures within our tests (Figure 6). To record temperature data, we positioned a rectangular measurement area along the entire length of the specimen's reduced section. Within this defined area, we meticulously logged the maximum temperature value observed during our experiments. This methodology is particularly advantageous for pinpointing the specimen's hottest surface region, which can serve as an indicator of potential stress concentrations or thermal anomalies. The thermal camera was placed in front of the specimens, maintaining an approximate distance of 300 mm, although variations in distance occurred based on the specific region of interest on the specimen. This meticulous positioning ensured accurate and focused temperature measurements. Data post-processing was executed using Altair, which is software integrated into the IR-camera system. This software was employed to analyze and manipulate the collected data.

Figure 7. 3D-Printed parts on bed plate

Figure 6. Testing setup

4. Results and discussions 4.1. Thermal analysis

The mechanical deformation of materials during tensile testing can lead to the generation of heat through processes like plastic deformation and energy dissipation. This is particularly pronounced in regions with higher stress, and the heat generated can be detected using thermography. Our analytical approach comprised two distinct phases. Firstly, we conducted a qualitative assessment by examining thermal maps as the primary diagnostic tool. Subsequently, we delved into a more detailed analysis, focusing on the thermal profile data. The utility of thermal mapping was evident in its ability to swiftly pinpoint the region with the highest temperature at the outset of each test. This temperature elevation corresponded to areas within the material structure characterized by defects and an increased likelihood of failure. Furthermore, the thermographic system allowed for continuous monitoring of damage evolution throughout the test duration. This dynamic process was visually tracked through corresponding thermal images, enabling real-time assessment of damage progression within the material specimen. The thermal profile exhibited a consistent pattern across diverse specimen types and can be delineated into distinct phases. Initially, we observe an initial phase characterized by a nearly linear temperature decrease. During this stage, the material displays complete elasticity, indicating that the mechanical energy imparted by the testing process is entirely absorbed and stored by the material. Subsequently, we encounter an intermediate phase where a non-linear, gradual decrease in temperature ensues. While the material's mechanical behaviour remains macroscopically elastic, subtle micro-damages are likely initiated. Finally, the thermal profile culminates in a final phase where temperature rises until eventual failure occurs. In this stage, the previously stored energy within the material is liberated, facilitating the creation of new damages and the expansion of pre-existing ones. This observed thermal profile furnishes valuable insights into the material's dynamic