Flexural monitoring of carbon fiber/epoxy composite by acoustic emission
محورهای موضوعی : فصلنامه شبیه سازی و تحلیل تکنولوژی های نوین در مهندسی مکانیک
نیما بهشتی زاده
1
(
دانش آموخته کارشناسی ارشد
)
امیر مصطفی پور
2
(
دانشیار / دانشگاه تبریز
)
کلید واژه: Acoustic Emission, Composite, Carbon fiber/epoxy, Load monitoring, Non-destructive test,
چکیده مقاله :
Carbon / epoxy composite is one of the most useful polymer matrix composites that has special properties such as high strength-to-weight ratio, high hardness, high corrosion resistance, Resistance to nuclear radiation has high consumption in different industries such as aerospace industry. Therefor monitoring of loading of this type of composite is important. In order to determine failure mechanisms, acoustic emission method has more performance than other non-destructive methods. In this research acoustic emission method was used to evaluate and monitoring of the carbon epoxy composite three point bending load. For this purpose bending behavior of composite and relationship between acoustic signals studied. Using both fast Fourier transform and wavelet transform method in this research, which led to the same result. Using FFT maximum frequency 140 KHZ was determined, that wavelet transform confirmed this result too. Time limits that events was occurred on the under load specimen, was monitored by online diagrams that obtained from acoustic system. Finally failure mechanisms of composite were confirmed by SEM pictures. Time limits and ascending progress of diagrams validates bending diagram.
کامپوزیت الیاف کربن/اپوکسی یکی از پرکاربردترین کامپوزیت‌های زمینه پلیمری می-باشد که به دلیل خواص ویژه‌ای از قبیل استحکام بالا نسبت به وزن، سفتی ویژه بالا، مقاومت خوردگی بالا و مقاومت در برابر تابش اتمی، مصرف بالایی در صنایع مختلف از جمله صنایع هوافضا دارد. به همین جهت مانیتورینگ بارگذاری این نوع کامپوزیت امری مهم است. به منظور شناسایی مکانیزم‌های خرابی کامپوزیت‌ها، روش آکوستیک امیشن کارایی بهتری در مقایسه با آزمون‌های غیر مخرب دیگر دارد. در این پژوهش از روش آکوستیک امیشن برای مانیتورینگ بارگذاری خمشی کامپوزیت الیاف کربن در زمینه اپوکسی استفاده شد. بدین منظور رفتار خمشی کامپوزیت و ارتباط آن با سیگنال‌های ساطع شده از نمونه تحت بارگذاری بررسی گردید. بکارگیری هر دو روش تبدیل فوریه زمان کوتاه و تبدیل موجک در این پژوهش، نتیجه یکسان آن‌ها را در پی داشت. با استفاده از تبدیل فوریه زمان کوتاه، فرکانس بیشینه در این بارگذاری در حدود 140 کیلوهرتز تعیین شد که روش تبدیل موجک نیز همین محدوده را تایید کرد. محدوده زمانی رویدادهای رخ داده در نمونه تحت بارگذاری توسط نمودارهای برخط به دست آمده از سیستم آکوستیکی مانیتور گردید و در نهایت مکانیزم‌های شکست کامپوزیت با تصاویر میکروسکوپ الکترونی روبشی تایید شد. محدوده‌های زمانی و روند صعودی نمودارها، صحت سنجی خوبی با نمودار خمشی بر جای گذاشت.
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