PSI - Issue 59

Viktoriia Ihnatieva et al. / Procedia Structural Integrity 59 (2024) 487–493 Viktoriia Ihnatieva/ Structural Integrity Procedia 00 (2019) 000 – 000

488

2

fractures, i.e., the emergence of foci of violation of the stability of the structure. On this basis, a complex-profile product with a more homogeneous and robust structure is more resistant to vibrational processes. Consequently, the quality of impregnation of material fibres in the manufacture of complex profile products made of composite materials influences the seismic resistance of the structure. The quality of the complex profile products from fibre composites depends on the quality of binder impregnation of reinforcing materials during the moulding process. This mainly applies to products manufactured by the pultrusion method. Such products are characterised by the formation of a braided layer of unimpregnated reinforcement. The impregnation of the reinforcement must be ensured in the process of subsequent technological processing of the product blank. Also, a number of tasks are solved to select methods and techniques of moulding the product, formation of its structural elements, design of the equipment used and parameters of the technological process (Freger et al., 2004; Freger et al., 1998; Vyshniakov et al., 2014; Gribanov et al., 2020; Bochkarev et al., 1988; Buketov et al., 2016). 2. Problem Statement The product is formed from a semi-finished product on a cylindrical mandrel in a pre-forming process. The preforming process consists of several stages and includes impregnation, squeezing, spreading of the main reinforcement on the surface of the mandrel, preforming, application of the annular braiding layer and calibration (Freger et al., 2004). At the same time, some amount of reinforcing components of the semi-finished product contains excess binder. At the same time, a sufficient amount of remaining binder is required to ensure a given degree of filling of each structural element. The purpose of this study is to determine the parameters that ensure the conditions of binder redistribution, impregnation quality and the necessary degree of filling of all elements. 3. Materials and results of research. The product profile is finalised after the calibration process. However, the presence of broaching operation leads to the necessity to separate the process of strut moulding and the process of shelf moulding. This separation of processes is due to the fact that broaching must be carried out according to the specified dimensions of the strut thickness, and the formed strut prevents the movement of the tool that carries out broaching. The strut is formed in two stages. At the first stage, a cylindrical semi-finished product is used to form a flat profile wall. For this purpose, design tasks such as centring of the profile, separation of the strut and shelf material, partial sealing of the strut material and fixation of the boundaries by broaching must be solved at the stage of equipment design. In this case, material compaction is carried out to join the semi-finished product parts that are in opposite parts. The pressure should not be high, as it is necessary to ensure sufficient freedom of movement of the fibres during broaching. Otherwise, the fibres of the base material will be destroyed and the strength of the resulting product will be reduced. The maximum value of this pressure must be less than or equal to the pressure that results from the deformation of the material elements (pre-tensioned) forming the strut. This pressure is determined by their tension and the radius of curvature of the surface to be compacted y R (Fig. 1).

3 PF

c

(1)

p



c

2

Fh R

c y

where c F - cross-sectional area of the profile strut; F - total square of the product profile; c h - height of the profile strut.