PSI - Issue 18

Lobanov Dmitriy S. et al. / Procedia Structural Integrity 18 (2019) 347–352

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Lobanov Dmitriy S. et al. / Structural Integrity Procedia 00 (2019) 000–000

structures. Experimental data on the impact of operating and climate temperatures on the mechanical properties of different classes of polymer composite materials are presented in following works [Kucher et al. (2013) and other]. The paper [Bai et al. (2008)] noted the nontrivial dependence of the loss modulus on the test temperatures for pultruded polyester E fiberglass. The paper [Fan et al. (2015)] presents the dependences of the strength and stiffness characteristics of a three-dimensional four-directional epoxy carbon fiber on time and temperature of exposure. There is a monotonous decrease in the characteristics with an increase in the exposure time and the base temperature. The aim of this work is experimental research and obtaining new data on the patterns of change in the deformation and strength characteristics and the staging of damage accumulation to structural layered-fibrous polymer composites after temperature aging. The method of acoustic emission (AE) is used as an additional method of diagnosing materials subjected to temperature aging to assessing their structural integrity. [Mouzakis et al. (2019) and other]. This method is also widely used in the diagnosis of various materials. [Shilova et al. (2016), Zubova et al (2019) and other] 2. Materials and methods 2.1. Materials Tensile tests on structural epoxy/ fiberglass composite samples with laying layers [0º / 30º / 0º / 60º] were performed. Temperature aging was carry out. Aging according to the modes presented in Table 1 were carried out. The appearance of the samples before and after temperature aging is presented (Fig. 1).

Table 1. Temperature aging modes Temperature aging, °С

Number of days

Number of samples

Without thermal exposure

-

5 6 4 3 3 6 6

120 120 160 160 200 200

5

15

5

15

5

15

22 °С

120 °С

160 °С

200 °С

After 5 days

After 15 days

Fig. 1. The appearance of the samples before and after temperature aging: after 5 days at different temperatures (а), after 15 days at different temperatures (b)

2.2. Experimental procedure Experimental research were performed of the Center of Experimental Mechanics PNRPU on an Instron 5882 universal electromechanical test system equipped with a temperature chamber with working temperatures from –100