Applicability of memory rules during cyclic stress–strain response of polymers PA6 and PA66 GF30

Durjava, Aleš (author), Nagode, Marko (author), Šeruga, Domen (author)

Polymers are rapidly emerging materials that are taking over the place in structural applications formerly reserved for metals. Structural materials require reliable load-bearing capability during the entire lifetime of products. Available simulation tools already offer constitutive models that are well applicable to metals but have not yet been approved for polymers. Typically, models with kinematic hardening incorporate Masing rule complemented by three memory rules to simulate the cyclic response of metals during variable loading. Conversely, the research presented here has been focused on polyamides as a load-bearing-capable substitute for metals in low-cycle fatigue applications. In particular, it has been studied whether natural PA6 and glass-fibre-reinforced PA66 GF30 follow the memory rules during variable amplitude loading. Incremental step tests were performed initially to determine the material parameters of the stabilised response. A high variation for the stabilised stress–strain response could reach up to 42.5% for PA6 and 24.5% for PA66 GF30 during incremental step tests. Moreover, the natural PA6 exhibited a higher degree of symmetry of the stress–strain result with less variation in stress than the reinforced PA66 GF30. Next, variable amplitude tests were performed which contained the three memory rules in the load history. The stress scatter during the variable amplitude loading in repeated tests has been observed between approximately 15% and 10% for natural PA6 and PA66 GF30, respectively. Finally, the Armstrong–Frederick model was used to carry out the simulations of the stress–strain response during the same variable load history. Comparison of the simulated and experimental results revealed that for both polymers, applicability of memory rules can be recognised.

• Language: English
• Keywords: polymers, memory rules, variable loading, plasticity, uniaxial, fatigue
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Author Accepted Manuscript
• Year: 2023
• Number of pages: 10 str.
• Numbering: Vol. 35, art. 106342
• PID: 20.500.12556/RUL-148421
• UDC: 539.214:678
• ISSN on article: 2352-4928
• DOI: 10.1016/j.mtcomm.2023.106342
• COBISS.SI-ID: 161846019
• Publication date in RUL: 22.08.2023

Record is a part of a journal

• Title: Materials today communications
• Publisher: Elsevier
• ISSN: 2352-4928
• COBISS.SI-ID: 19385622

Secondary language

• Language: Slovenian
• Keywords: polimeri, spominska pravila, spremenljivo obremenjevanje, plastičnost, enoosno utrujanje

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0182
• Name: Razvojna vrednotenja