الموضوع: ثبات السيراتو !!!!!!!؟

المشاركة الأصلية كتبت بواسطة amr mokhtar

شكرآ جدآ على المعلومات دى
انا فعلآ لم أنتبه للموضوع ده من قبل

بس انا عايز أفهم حاجة
من graph اللى موجود فى الموقع اللى حضرتك حطيته
تعليق السيراتو الخلفى يعتبر under damping و بكده فهو عند سرعة معينة يقرب من resonance و قد تكون السرعة دى هى اللى إحنا بنمشى عليها عادة عشان كده بنحس bounce

بس حسب graph ان التعليق ده بيتحسن جدآ بعد السرعة دى و بيدى أقل vibration ratio

اتمنى إنى أكون فهمت صح؟؟

Thanks Amr for the interest. The damping ratio (over, under...etc) is dependent on suspension (spring, damper) and mass of the car. Suspension characteristics would stay unchanged but the mass can vary. Most passenger cars are designed to be around critical or lightly overdamped if the driver is the only person on board. if you are carrying a lot of load (4,5 people) this will result in increasing the mass of the car and the system to be underdamped. That's why loaded cars experience obvious oscillating bounce when ran over a road bump. Resonance is more dangerous in underdamped cars and can only cause a problem around a specific car speed. if you increase or decrease the speed away from this resonance speed you will be fine and the vibration bounce will damp out. This is what some times happen over bumpy bridges in which each bridge segment is not aligned to the next. driving your car over this bridge around resonance speed would cause the car to enter an oscillating bouncy mode. this is very dangerous as if it is left going with the same speed, the car ends up having brief fly and possibly loss of control. You would need to reduce the speed (or increase it, but not favorable) to get away from resonance
I will be glad to answer any of your questions. Thanks again for the interest.


Dr. Yasser Zeyada
Mechanical Design Department
Faculty of Engineering
Cairo University