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Article
Vibration Analysis of Cross-Ply Plates Under Initial Stress Using Refined Theory
تحليل الاهتزازات تحت تاثير الاجهاد الاولي باستخدام نظرية اللوحة المكررة

Authors: Ibtehal Abbas Sadiq ابتهال عباس صادق --- Kani Hussein Bawa كاني حسين باوة
Journal: Al-Khwarizmi Engineering Journal مجلة الخوارزمي الهندسية ISSN: 18181171 23120789 Year: 2018 Volume: 14 Issue: 4 Pages: 34-44
Publisher: Baghdad University جامعة بغداد

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Abstract

Natural frequency under initial stresses for simply supported cross-ply composite laminated plates (E glass- fiber) are obtained using Refind theory (RPT). This theory accounts for parabolic distribution of the transverse shear strain through the plate thickness and satisfies the zero traction boundary conditions on the surfaces of the plate without using shear correction factors. The governing equations for Eigen value problem under initial stress are derived using Hamilton’s principle and solved using Navier solution for simply supported cross-ply symmetric and antisymmetric laminated plates. The effect of many design factors such as modulus ratio, thickness ratio and number of laminates on the Natural frequency and buckling stresses of orthotropic plates are studied. The results are compared with other researcher.

يتم الحصول على التردد الطبيعي تحت الضغوط الأولية للحصول على صفائح الرقائق المتقاطعة للـ (simply supported) باستخدام نظرية (Refind plate)هذه النظرية مسؤولة عن التوزيع المكافئ لسلالة القص المستعرض عن طريق سماكة اللوح وتلبي الشروط الحدودية للجر صفر على أسطح الصفيحة دون استخدام عوامل تصحيح القص. يتم اشتقاق المعادلات الحاكمة لمشكلة قيمة Eigen تحت الإجهاد الأولي باستخدام مبدأ هاملتون ويتم حلها باستخدام حل (Navier ) للألواح الطبقية المتناظرة المتماثلة وغير المتماثلة للـ (Simply supported). تم دراسة تأثير العديد من عوامل التصميم مثل نسبة المعامل (E1 / E2) ونسبة السمك ( (a / h وعدد الصفائح ( (N على التردد الطبيعي والضغط على الألواح المحبوسة. تتم مقارنة النتائج مع باحثين اخرين.


Article
Study the Effected Parameters on Vibration Analysis of Cantilever Beam with a Bolted Joint

Authors: Nathera A. Saleh نظيرة صالح --- Zainab Asaad Hardan زينب اسعد حردان
Journal: Basrah Journal for Engineering Science مجلة البصرة للعلوم الهندسية ISSN: Print: 18146120; Online: 23118385 Year: 2018 Volume: 18 Issue: 2 Pages: 26-39
Publisher: Basrah University جامعة البصرة

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Abstract

The main objective of the present paper is to study thevibration behavior of cantilever beam with a bolted joint ofdifferent lap’s type (i.e. Single lap, Double lap) for free andforced vibration. The effects of various parameters such as beamconfiguration, preload, harmonic force magnitude and harmonicforce positions on natural frequency, mode shape, and amplitudehave been investigated. The experimental work carried outduring this study included material selection, chemicalcomposition test, tension test, preparation configurations ofbeam, free and forced vibration tests at per- torques range (6-60N.m) and at rotational speeds range (300-900RPM).Numerically, a general purpose finite element method (ANSYSVer.16.1 package) has been used. The results show that thenatural frequencies of single lap (1Bolt, 2Bolt) bolted beams wereroughly equal to those of intact beam. But, in double lap boltedbeam were slightly lower than those of intact beam with sameprofile. Moreover, as preload or pre-torque on the bolt increases,the natural frequency becomes constant for all types of beamconfiguration. For forced vibration, the vibration amplitude islargely dependent on magnitude and position of harmonic force.The validation results present a good agreement with numericalresults as the largest margin of error is about (5%)


Article
Free Vibration Analysis of Perforated Laminated Composite Square Plates

Authors: Mohammed Salih Hassan AL-Araji1 --- Ali Sadik Gafer2 --- Raad Salman Saed3
Journal: Journal of University of Babylon مجلة جامعة بابل ISSN: 19920652 23128135 Year: 2018 Volume: 26 Issue: 10 Pages: 335-345
Publisher: Babylon University جامعة بابل

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Abstract

This paper presents a study of free vibration of perforated laminate composite plate. The modal characteristics consist of three layers, the material is hard orthotropic composite material, with simply support (SSSS), Clamped boundary (CCCC) and simple clamed conditions (SCSC) are applied at all four edges of the plate.. The natural frequency and mode shape of the plateshave been obtained using ANSYS 15. Eight-node isopaprametric layered shell elements (SHELL 281) are employed in the modeling for describing the vibrations of these perforated laminate composite plates. The effect of number of holes, hole area ratio, lamination angles and boundary condition on vibrations are investigated.The convergence study wasachieved for numerically and compare with present literature.The results showed that the frequencies of the plate with one hole at the center are different from the perforated plate when maintaining a fixed ratio hole area, as well the lamination angle has a clear effect on the increase and decrease of the fundamental frequencyfor all the tested cases.

تقدمهذهالورقة دراسةالاهتزازالحرللوحة‘طبقية مركبةومثقبة. وتتكونخصائصالنموذجمنثلاثطبقات،معالشروطالحدودية (اسناد بسيط، ثابت واسناد ثابت وبسيط)فيجميع الحواف. وقدتمالحصولعلىالترددالطبيعيوشكلالتشوهللألواحباستخدام طريقة العناصر المحددة حزمة. (ANSYS 15) تمالتحققمنتأثيرعددالثقوبونسبةالمساحة الثقوب, زاوية التصفيح والشروط الحدودية علىالاهتزازات. تمدراسةالتقارب النماذجوعمل مقارنةمعالباحثينالمقدمين.أظهرتالنتائجأنتردداتالصفيحةذاتالثقبالواحدفيالمركزتختلفعنالصفيحةالمثقبةعندالمحافظةعلىنسبة مساحةثقبثابت،وكذلكلزاويةالتصفيحتأثيرواضحعلىزيادةوتقلصالترددالأساسيلجميعالموديلاتالحالية،وعندكلالشروطالحدودية.

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