Mechanical Engineering - Theory Of Machines Lab

Product Details:

Torsional vibrations are often observed in belt-driven systems. With appropriate excitation of resonances, large vibration amplitudes can occur, which can lead to strong loads on shafts and gears, potentially resulting in damage. The TM 140 unit can be used to produce free and forced torsional vibrations and to study the effects of torsional stiffness, mass and damping on frequency and amplitude.

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Every reciprocating engine generates mass forces. The mass forces of the oscillating masses cannot be compensated completely, while the mass forces of the rotating masses are fully compensated. By using several cylinders it is possible that the forces compensate each other. However, disturbing moments may still occur. The experimental unit TM 180 enables investigation of the free masses and moments of a reciprocating engine with a single cylinder, with two cylinders or with four cylinders.

Product Details:

Critical speed and resonance are phenomena that play essential roles in many machines and systems. In particular, resonance states with impermissibly high vibration amplitudes can occur in rotating shafts and rotors at certain speeds, which in some cases can even lead to destruction of the machine. To prevent this, the system is operated well above or below the critical speed and driven quickly through the critical speed range. Therefore, knowledge of critical speeds and vibration modes is important in the design and operation of machines with bending elasticity in their rotors.

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Imbalances on rotating machines are often the cause of disruptive vibrations and noise. During imbalance, the principal axis of inertia or centre of gravity of the rotating machine component is outside its axis of rotation. By adding or removing masses, the centre of gravity or the principal axis of inertia can be shifted so that both coincide with the axis of rotation. This process is called balancing. The machine component is then balanced and runs without vibration.

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The terms “critical speed” and “resonance” are often used when referring to rotating systems. Resonance occurs when the natural frequency and the excitation frequency match. The natural frequency of an oscillatory system is that frequency at which the system oscillates with the associated natural mode after a single excitation. Operation at critical speed can damage the system because of the high vibration amplitudes. In order to study the phenomenon of shaft vibration in more detail, there are two simplified calculation models. In the first case, the mass of the elastic shaft is evenly distributed along its length. In the second case, the shaft consists of massless, elastic shaft sections and the masses are combined into discrete mass disks.

Product Details:

The TM 150 vibration trainer can be used to study many topics from the field of vibration theory through experimentation.

The topics range from simple pendulum-swinging forced vibrations with resonance to vibration absorption.

The central element of the vibration trainer is a sturdy profile frame, to which the different experimental setups are easily attached. The extensive accessories are housed in a mobile laboratory table with drawers. In addition to free vibrations, forced vibrations can also be represented by means of an electric motor imbalance exciter. The excitation frequency is set and displayed on a control unit.

An oil damper allows the study of damped vibrations with adjustable damping ratios. Vibration absorbing is demonstrated with a tuneable bending oscillator. A mechanical drum and a polar chart recorder make it possible to record vibrations.