Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

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Access Right: Closed AccessSubject: search.filters.subject.Fracture toughness

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  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Mechanical Properties of Palygorskite Clay Stabilized With Polyelectrolytes
    (Elsevier, 2023) Huang, Jianxin; Makhatova, Ardak; Kogbara, Reginald; Masad, Eyad; Sukhishvili, Svetlana; Little, Dallas
    Two polyelectrolytes of opposite charges, sodium polystyrene sulfonate (PSS) and polydiallyldimethylammonium chloride (PDADMAC), were investigated to stabilize palygorskite clay at varying dosages of 0.2, 0.8, 1.6, and 3.2 % by the dry weight of the soil. Both PSS and PDADMAC improved the unconfined compressive strength of the palygorskite clay. PSS was effective at all the polymer contents studied after 7 days of dry curing and the strength increased with the dosages of PSS added, ranging from 2 MPa (0.2 % PSS) to 3.1 MPa (3.2 % PSS), compared with 1.5 MPa of the untreated soil. PDADMAC, on the other hand, showed comparable strength improvements as PSS did at the high polymer contents of 1.6 and 3.2 % but did not work at 0.2 and 0.8 % dosages. Under wet curing at 100 % relative humidity, PSS improved the strength of the clay by 40 % (620 kPa at 0.2 % PSS) to 77 % (764 kPa at 1.6 % PSS) compared to the untreated clay (440 kPa). PDADMAC exhibited less improvement than PSS under wet conditions but still worked at dosages of 0.8 and 1.6 %. Besides strength, the resilient modulus and fracture toughness of the treated specimens increased by approximately 10 % and 66 %, respectively, when treated with 1.6 % PSS, which was the optimum content based on the strength results. PDADMAC-treated palygorskite, however, exhibited cracking during curing for both tests, showing potential drying crack issues. The adsorption of PSS and PDADMAC on palygorskite clay were also measured using ultraviolet–visible spectroscopy, and binding between these polymers and palygorskite has been confirmed. The measured adsorption capacities of PSS and PDADMAC were comparable (2.9 and 2.7 mg/g, respectively), while the PSS was somewhat more efficient in improving soil mechanical properties. © 2023 Elsevier Ltd
  • Article
    Citation - WoS: 23
    Citation - Scopus: 26
    Experimental and Statistical Analysis of Carbon Fiber/Epoxy Composites Interleaved With Nylon 6,6 Nonwoven Fabric Interlayers
    (SAGE Publications Inc., 2020) Beylergil, Bertan; Tanoğlu, Metin; Aktaş, Engin
    Thermoplastic interleaving is a promising technique to improve delamination resistance of laminated composites. In this study, plain-weave carbon fiber/epoxy composites were interleaved with nylon 6,6 nonwoven fabrics with an areal weight density of 17 gsm. The carbon fiber/epoxy composite laminates with/without nylon 6,6 nonwoven fabric interlayers were manufactured by VARTM technique. Double cantilever beam fracture toughness tests were carried out on the prepared composite test specimens in accordance with ASTM 5528 standard. The experimental test data were statistically analyzed by two-parameter Weibull distribution. The results showed that the initiation and propagation fracture toughness Mode-I fracture toughness of carbon fiber/epoxy composites could be improved by about 34 and 156% (corresponding to a reliability level of 0.50) with the incorporation of nylon 6,6 interlayers in the interlaminar region, respectively. The results also revealed that the percent increase in the propagation fracture toughness value was 67 and 41% at reliability levels of 0.90 and 0.95, respectively.