PSI - Issue 79

Volodymyr Hutsaylyuk et al. / Procedia Structural Integrity 79 (2026) 501–507

502

1. Introduction The preloading state has a pronounced effect on the subsequent deformation and fatigue behaviour of aluminium alloys, as shown by Kocańda et al. (2014). Preliminary combined loading (PCL) results in a reduction of fatigue life: the number of cycles to failure decreases compared to the reference material without preloading. After such loading, localized plastic flow develops, persistent slip bands (PSBs) are formed, the fracture surface morphology is altered, and, as a consequence, the resistance to crack initiation and early crack growth is reduced, as demonstrated in previous studies by Hutsaylyuk et al. (2013, 2015). The effect of short dynamic impulses on the deformation behaviour of aluminium alloys has been systematically studied in the framework of dynamic non-stationary processes (DNP). When a short impulse is applied during monotonic tensile loading, the material enters a non-stationary deformation regime characterized by high-frequency stress–strain oscillations (1–2 kHz) and local strain-rate fluctuations of 1–60 s⁻¹. These oscillations disturb the quasi equilibrium state of the material, induce energy redistribution between defect subsystems, and trigger defect self organization processes. The impulse loading modifies the initial stress–strain state, promotes heterogeneous dislocation structures, and activates additional plastic deformation mechanisms such as localized slip and subgrain rearrangements, which may increase crack growth resistance, as shown by Hutsaylyuk et al. (2016). From an energetic perspective, the external energy of a short impulse can be fully absorbed by the material and consumed in the formation of new structural states or dissipative structures. These localized microstructural transformations are manifested in the macromechanical response of the material, affecting the subsequent mechanical behaviour under primary loading. These phenomena are of particular importance for structural alloys used in aerospace applications. 2024-T351 aluminium alloy is characterized by a favourable strength-to-weight ratio and good fatigue resistance, making it widely used in aircraft structures such as wing skins, frames, and fuselages. Testing of 2024-T351 aluminium alloy under non-stationary loads with additional force impulses is crucial for accurately determining its strength and fatigue resistance in real flight conditions. This enables the validation of computational models and the optimisation of structural designs. Here introduce the paper, and put a nomenclature if necessary, in a box with the same font size as the rest of the paper. The paragraphs continue from here and are only separated by headings, subheadings, images and formulae. The section headings are arranged by numbers, bold and 10 pt. Here follows further instructions for authors. 2. Material and test procedure Experimental studies were carried out on flat specimens made of the 2024-T3 aluminium alloy — a conventional Al–Cu–Mg alloy widely used in aircraft structures. This alloy is characterized by a favourable strength-to-weight ratio and good fatigue resistance, which makes it suitable for structural components such as wing skins, frames, and fuselage panels. The specimens were cut along the rolling direction and had a thickness of 3 mm and a gauge width of 15 mm. The chemical composition of the base material are given in Tables 1.

Table 1. Chemical composition of 2024-T3 aluminium alloy. %

Si

Fe

Cu 4,7

Mn

Mg 1,5

Cr

0,05

0,13

0,70

0,01<