Performance Analysis of Multibody Mechanical Systems with Imperfect Flexible Joints.

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Bibliographic Details
Title:	Performance Analysis of Multibody Mechanical Systems with Imperfect Flexible Joints.
Authors:	Alshaer, Bassam J.¹ bjalshaer@just.edu.jo, Lankarani, Hamid M.², Al-Shyyab, Ahmad S.¹, Alfreahat, Ali B.¹
Source:	Jordan Journal of Mechanical & Industrial Engineering. Mar2026, Vol. 20 Issue 1, p29-36. 9p.
Subjects:	Multibody systems, Slider-crank mechanisms, Vibration (Mechanics), Range of motion of joints, Finite element method, Mechanical loads, Equations of motion
Abstract (English):	Multibody mechanical systems consist of interconnected bodies joined by various joints. Joint imperfections, often stemming from wear, introduce clearances that result in impacts. To mitigate these effects, soft-material bushes are employed to add flexibility. This research evaluates the combined impact of joint flexibility and imperfections on system performance. A mathematical model for the dynamic equations of motion is formulated. The performance of a crank-slider mechanism with imperfect, flexible joints is examined using advanced commercial software that integrates Multibody System dynamics with the Finite Element Method. The findings indicate that while mechanisms with ideal rigid joints exhibit optimal performance, such joints are impractical; inherent clearances generate significant impact forces and peaks in the crank's actuating torque. The results demonstrate that flexible joints attenuate these torque peaks by nearly half. However, this flexibility introduces vibrations, which affect the mechanism's overall performance. This study compares mechanisms with flexible imperfect joints against those with perfect and imperfect rigid joints. Although flexible imperfect joints reduce torque peaks by approximately 50%, they introduce low-amplitude vibrations due to elasticity. Furthermore, simulations show that joint flexibility redistributes contact forces, decreasing the severity of impact stresses that typically accelerate wear and fatigue. These findings indicate that incorporating controlled flexibility into imperfect joints can substantially enhance operational smoothness and durability. Overall, this study provides critical insights for designing more reliable mechanical systems, particularly where joint clearances are unavoidable. [ABSTRACT FROM AUTHOR]
Abstract (Arabic):	يركز المقال على تحليل أداء الأنظمة الميكانيكية متعددة الأجسام (MBS) ذات المفاصل المرنة غير المثالية، مع دراسة خاصة لآلية ذراع التوصيل (الكرنك-سلايدر) التي تتضمن فراغات في المفاصل ومرونة في البوشنغ (الكم). باستخدام نموذج رياضي قائم على صياغة الإطار العائم للمرجع (Floating Frame of Reference Formulation - FFRF) مقترن بمحاكاة طريقة العناصر المحدودة (Finite Element Method - FEM)، تقارن الدراسة بين أربعة تكوينات للمفاصل: مفاصل صلبة-مثالية، صلبة-غير مثالية (مع فراغات)، مرنة-مثالية، ومرنة-غير مثالية. تظهر النتائج أن البوشنغات المرنة في المفاصل غير المثالية تقلل بشكل كبير من قوى الصدمة القصوى وعزم التفاعل بنسبة تقارب 50% مقارنة بالمفاصل الصلبة ذات الفراغات، حيث تستبدل الذبذبات الحادة لقوى الصدمة بتذبذبات أكثر سلاسة وتخميدًا، وإن كان ذلك على حساب ظهور اهتزازات منخفضة السعة. يكشف تحليل الإجهاد أن المرونة تعيد توزيع قوى التلامس، مما يخفف من ذروات الإجهاد عند واجهة الدبوس-البوشنغ، وهو ما له تأثيرات مهمة على التآكل والإجهاد المتكرر. تسلط النتائج الضوء على أهمية تحسين صلابة وتخميد البوشنغ لتحقيق توازن بين امتصاص الصدمات والسيطرة على الاهتزازات، مما يعزز من متانة وأداء الأنظمة الميكانيكية الديناميكي في الحالات التي لا يمكن فيها تجنب فراغات المفاصل. [Extracted from the article]
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Database:	Engineering Source

Description
Abstract:	Multibody mechanical systems consist of interconnected bodies joined by various joints. Joint imperfections, often stemming from wear, introduce clearances that result in impacts. To mitigate these effects, soft-material bushes are employed to add flexibility. This research evaluates the combined impact of joint flexibility and imperfections on system performance. A mathematical model for the dynamic equations of motion is formulated. The performance of a crank-slider mechanism with imperfect, flexible joints is examined using advanced commercial software that integrates Multibody System dynamics with the Finite Element Method. The findings indicate that while mechanisms with ideal rigid joints exhibit optimal performance, such joints are impractical; inherent clearances generate significant impact forces and peaks in the crank's actuating torque. The results demonstrate that flexible joints attenuate these torque peaks by nearly half. However, this flexibility introduces vibrations, which affect the mechanism's overall performance. This study compares mechanisms with flexible imperfect joints against those with perfect and imperfect rigid joints. Although flexible imperfect joints reduce torque peaks by approximately 50%, they introduce low-amplitude vibrations due to elasticity. Furthermore, simulations show that joint flexibility redistributes contact forces, decreasing the severity of impact stresses that typically accelerate wear and fatigue. These findings indicate that incorporating controlled flexibility into imperfect joints can substantially enhance operational smoothness and durability. Overall, this study provides critical insights for designing more reliable mechanical systems, particularly where joint clearances are unavoidable. [ABSTRACT FROM AUTHOR]
ISSN:	19956665
DOI:	10.59038/jjmie/200103