مهندسی مکانیک مدرس

مهندسی مکانیک مدرس

بررسی تئوری و تجربی سازه سلولی جدید با تخلخل هدفمند شعاعی ساخته‌شده به روش ساخت افزایشی و بهینه‌سازی خواص مکانیکی

نوع مقاله : پژوهشی اصیل

نویسندگان
گروه مهندسی خودرو، دانشکده مهندسی مکانیک، دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران، ایران
چکیده
با توجه به پیشرفت‌هایی که در تکنیک‌های ساخت افزودنی صورت گرفته، امکان طراحی و تولید سازه‌های سلولی با هندسه‌های پیچیده با خواص مکانیکی مناسب و وزن کم فراهم آمده ‌است و استفاده از مواد سلولی متخلخل در بسیاری از زمینه‌ها در حال افزایش است. در پژوهش حاضر سازه استوانه‌ای نوینی که در راستای شعاعی توزیع چگالی نسبی و خواص گرادیانی قابل تنظیم دارد، با الهام از ساختار استخوان طراحی و معرفی شده ‌است. سازه سلولی در ۵لایه و از تکرار سلول واحد پایه چهاروجهی منتظم با الگوی مشخص در راستای شعاعی، محیطی و محوری حاصل شده ‌است. با استفاده از روابط تحلیلی، خواص مکانیکی الاستیک سازه تعیین شده است. حل تئوری ارایه‌شده به‌کمک مدل‌سازی عددی و ساخت افزایشی نمونه پلیمری به روش سنگ‌چاپ سه‌بعدی و آزمون آن صحه‌گذاری شده ‌است. مقایسه نتایج بیان‌گر دقت مناسب حل تئوری است. همچنین اثر متغیرهای هندسی طراحی شامل ارتفاع المان حجمی تکرارشونده، تعداد اضلاع چندضلعی آغازگر و قطر یال‌ها بر روی خواص مکانیکی سازه و توزیع آنها مطالعه شده ‌است. با استفاده از الگوریتم‌های ژنتیک بهینه‌سازی تک‌هدفه و چندهدفه خواص الاستیک سازه انجام شده‌ است. نتایج بهینه‌سازی تک‌هدفه در سازه‌هایی با تخلخل‌های ۷۰، ۷۵ و ۸۰% به‌ترتیب بهبود ۳۲/۹، ۳۵/۹۲ و ۳۵/۶۸% مقدار مدول الاستیسیته بر جرم و افزایش ۱۱۶/۳۵، ۹۶/۴۸ و۷۳/۶۲% مقادیر تنش تسلیم بر جرم در همین تخلخل‌ها، نسبت به سازه مبنا با تخلخل‌های مشابه را نشان می‌دهند. نتایج حاصل، بیان‌گر قابلیت مناسب سازه برای ایجاد توزیع متغیر خواص و تخلخل و پتانسیل کاربرد آن به‌عنوان بافت جایگزین استخوان مصنوعی است.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

New Additively Manufactured Cellular Lattice Structure; Theory and Experiment

نویسندگان English

N. Mohtadifar
M. Asgari
Automotive Engineering Department, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran
چکیده English

Due to developments in additive manufacturing (AM) techniques, design and producing cellular structures with complex topologies accompanied with appropriate mechanical properties and lightweight have become possible and the application of cellular porous materials has been increasing in various areas. In the current study, a novel cellular structure with adjustable radially graded relative density and properties inspired by bone tissue structure is designed and introduced. The cellular structure has five layers and is achieved by repeating a regular four-sided unit-cell in radial, peripheral, and axial directions by a specific pattern. Next, using analytical relations, the mechanical properties of the structure are derived. The obtained theoretical solution is validated by numerical modeling and experimental test of a polymeric specimen manufactured by SLA method. Comparison of the results shows good precision of the theoretical solution. Furthermore, the effect of design parameters including the height of representative volume element, the number of the sides of start shape, and radius of the struts on mechanical properties and their distribution is studied. Using genetic algorithms single-objective and multi-objective optimization is performed on elastic properties of the structure. The single-objective optimization results for structure with 70, 75, and 80% porosities led to 32.9, 35.92, and 35.68% improvement of elastic modulus to mass, respectively and 116.35, 96.48, and 73.62% increase of yield strength to mass at similar porosities compared to base models with same porosities. The results show proper ability of the structure in creating distribution of mechanical properties and porosity and its potential capability for use in bone replacement applications.

کلیدواژه‌ها English

Porous Cellular Material
Radially Graded Porosity
Additive Manufacturing
Analytical Solution
Finite Element Modeling
multi-objective optimization
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