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1

The influence of the ageing-fatigue degradation on the mechanical properties of glass-reinforced composites

Szymiczek M., Rojek M., Wróbel G.

Polish Journal of Chemical Technology

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2016

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Vol. 18, nr 1

113--119

EN

Drawing up diagnostic relations between thermal characteristics determined in thermal imaging examinations and mechanical properties, allowing for forecasting the state of material during the use, was a purpose of the work. Research was performed on polyester – glass composites which were subjected to the ageing-fatigue degradation process in a device created specifically for that purpose. It was indicated how to assess the degree of the decline, taking into account the fall in material strength properties. The basis of a method was measurement of changes in temperature in activated thermal processes. Relations between changes of the speed of heating and cooling were related to the bending strength and the modulus of elasticity. Diagnoses were backed up with microscopic examinations.

2

Mechanical properties evaluation and ultrasound diagnosis of unsaturated polyester-glass pipes

Wróbel G., Rojek M., Szymiczek M.

Polish Journal of Chemical Technology

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2015

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Vol. 17, nr 2

77--83

EN

The purpose of the present work was the elaboration of research methodology of the exhaustion degree of performance properties of pipes based on unsaturated polyester and glass fibers, which were manufactured by the cross winding method on a poly(vinyl chloride) core. Within the frame of the work we conducted fatigue-ageing tests being the simulation tool of the degradation process of polyester-glass pipes. Diagnosis of the composite material condition was conducted with the use of nondestructive ultrasonic testing with the application of the echo method, in which the transition time of ultrasonic wave was determined as the identifying parameter. The registered transition time of ultrasonic wave allowed the identification of the material condition during the course of pipes exploitation.

3

The effect of fiber content on the ultrasonic wave velocity in glass/polyester composites

Wróbel G., Pawlak S.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

295-298

EN

Purpose: The primary purpose of the present study was to find relationship between ultrasonic wave velocity and the fiber content in glass/polyester composites. In addition, further tests were conducted to determine how other factors can affect the ultrasonic velocity. Design/methodology/approach: Experimental data have been obtained using ultrasonic wave velocity measurements and standard destructive analysis. For ultrasonic non-destructive testing, through-transmission technique was used. Findings: Experimental results have shown that the longitudinal wave velocity increases almost linearly with an increase of the fiber content in investigated specimens. Research limitations/implications: The propagation velocity of the ultrasonic waves can be affected, apart from fiber content, by interfacial stresses and changes of elastic modulus in polymer matrix during long-lasting conditioning. These factors overlap and which of the two can affect the ultrasonic wave to a higher degree is yet to established. Further work is needed in this area. Practical implications: Ultrasonic wave velocity measurement seems to be an effective method of fiber content evaluation, but for any different composites, distinct relationships should be determined. Originality/value: The results obtained would be of considerable importance in industrial applications to achieve a first estimate of fiber content variations in composite materials.

4

A method for ultrasonic quality evaluation of glass/polyester composites

Wróbel G., Wierzbicki Ł., Pawlak S.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 12

729-734

EN

Purpose: The aim of the present study was to find relationship between the ultrasonic wave velocity or attenuation coefficient and the local fiber content in glass/polyester composites. Design/methodology/approach: Experimental data have been obtained using ultrasonic wave velocity and attenuation measurements. To determine the actual fiber content in the composites, needed to build proper relationships between considered factors, the standard destructive analysis was applied. For ultrasonic nondestructive testing, through-transmission technique was used. Findings: Experimental results have shown that the longitudinal wave velocity increases almost linearly with an increase of the fiber content in the investigated specimens. The second considered parameter of an ultrasonic wave, namely attenuation coefficient was not correlated with the glass content. Research limitations/implications: The propagation velocity of the ultrasonic waves can be affected, apart from fiber content, by interfacial stresses and changes of elastic modulus in polymer matrix during long-lasting service time. These factors overlap and which of the two can affect the ultrasonic wave to a higher degree is yet to established. Further work is needed in this area. Practical implications: The described method can be applied to the post-production quality control of a finished composite product, but in the case of composites made of different constituent materials it is necessary to determine distinct relationships for each composite. Originality/value: The results obtained would be of considerable importance in the industrial applications to achieve a first estimate of fiber content variations in polymer composite materials.