21289

21289

مطالعه تجربي كاربرد الياف طبيعي در اتصالات چسبي به منظور بهبود خواص استحكامي اتصالات

كارشناسي ارشد

مهندسي هوافضا

1396

1398/8/4

دكتر مجيدرضا آيت اللهي

دكتر عليرضا اخوان صفار

مكانيك

پژوهش‌گران زيادي بر بهبود استحكام چسب‌ها به كمك الياف نخل خرما تحت حالت نمونه بالك يا در كامپوزيت‌هاي زمينه پليمري مطالعه كردند. در اين پژوهش بهبود استحكام اتصالات چسبي تك لبه توسط الياف نخل خرما بررسي شده است. جهت مطالعه استحكام بخشي الياف، چهار پارامتر شامل؛ اندازه طول، شستشوي قليايي، درصد وزني و محل نمونه برداري الياف توسط آزمون كشش بررسي شده است. همچنين سطوح اتصالات پس از شكست جهت بررسي مكانيزم‌هاي اسيب توسط ميكروسكوپ نوري تصوير برداري گرديده است. مطابق نتايج آزمايش كشش اتصالات چسبي تك لبه تقويت شده استفاده از 2% وزني الياف شاخه نخل خرما كه با محلول 6% وزني قليايي سديم هيدروكسيد شستشوي قليايي شده و سپس بصورت الياف كوتاه (5/0 الي 2 ميلي‌متر) به لايه چسب اپوكسي افزوده گرديده، توانسته است استحكام برشي اتصالات چسبي تك لبه را به مقدار % 140 افزايش دهد. هم‌چنين تصاوير تهيه شده از سطوح شكست حاكي از مكانيزم‌هاي مختلف آسيب است كه نشان ‌مي‌دهند الياف نخل خرما با تحمل بار و توقف رشد ترك در لايه چسب توانسته‌اند بخوبي استحكام اتصالات چسبي تك‌لبه را بهبود بخشند. واژه‌هاي كليدي: اتصالات چسبي، الياف طبيعي، الياف نخل خرما، شستشوي قليايي، مكانيزم‌هاي آسيب

1398/08/20

Experimental study of the use of natural fibers in adhesive joints to improve the strength of them

10/26/2019 12:00:00 AM

Nowadays, the adhesive joints have particular use in many industries especially in the aerospace. However, a variety of loading and environmental conditions cause adhesive joints not to be able to support the needs of some joints. Therefore, the researchers have tried to enhance their mechanical properties by adding variety of materials to the adhesive layer. Synthetic and natural additives have been used to strengthen the adhesive joints. Studies have shown that the use of natural fibers has been considered due to their biodegradability and environmental compatibility in contrast with synthetic fibers. The natural fibers are usually disposed of in the form of scrap in annual pruning. Therefore, their use in the adhesive industry can lead to the production of highly economical and strong products. Due to the abundance of date palm trees in the world, especially in Iran, it is important to use fiber in order to improve adhesive joints. Many researchers have studied the improvement of adhesive strength by date palm fibers in form of balk or composite samples. In this study, the improvement of the strength of single lap adhesive joints (SLJ) by date palm fibers was investigated. Along with this purpose, four parameters including size, alkaline solution concentration, weight ratio and fiber sampling location were investigated by tensile test. According to the results, adding 2 wt% of branch short fibers (0.5 to 2 mm) treated by 6 wt% alkaline solution to the epoxy adhesive layer enhanced the SLJ’s strength up to 140%. In the following, to investigate the micro mechanisms of failure, the fractured surfaces were analyzed. The results show that the date palm fibers can improve the strength of adhesive joints by slowing down the crack propagation, absorbing energy and load endurance. Keywords: Adhesive joints, natural fibers, date palm fibers, alkaline treatment, failure mechanisms