Universal Vibration Apparatus HVT12 Modular design means additional options can be acquired as and when budgets permit Uses non-contacting devices - LVDT and a proximity sensor to minimise unnecessary damping Easier to set-up and run than a pencil, trace and rotating drum apparatus Two-channel digital oscilloscope Data acquisition system with computer-linking supplied as standard for data capture, storage, analysis and printing Two year Warranty
Introduction Vibration of mechanical systems is important because it can cause one or more of the following undesirable effects, amongst others: Structural failure due to excessive displacement and stress Fatigue failure due to repeated stress reversal Malfunction of mounted equipment and components Noise Slippage and dislocation of joints Wear due to relative motion between components Discomfort of transported or mounted persons Vibration transmission to connected structures Positive feedback leading to catastrophic failure Vibration can be exploited for positive purposes such as transporting powder, sieving and sizing products, consolidating poured concrete, applying massage, speeding up chemical reactions, removing dental plaque, and many other applications. The HVT12 is designed to illustrate the vibrational characteristics and controlling properties of a simple mechanical system. It illustrates how it is possible to suppress the vibration of a primary system by attaching to it a smaller secondary system. The Standard HVT12 Universal Vibrations Apparatus comprises the following equipment: HVT12f - Vibrations Frame HVT12g - Free and Forced Vibrations experiment HVT12d - Vibration Absorber HVT12k Data Acquisition System (Two Channel Digital oscilloscope) HAC90 Tachometer HAC110 Speed Controller HAC120 Motor Exciter Experimentation on the following four phenomena is possible with the standard unit: Free Vibrations Forced Vibrations Resonant Frequency Damping The modular nature of the standard unit allows optional extras to be added as and when budgets permit. Essential Options for Requirements for Module Operation Module Code Module Description HVT12f Vibrations Frame HVT12d Vibration Absorber HVT12k Data Acquisition System HAC90 Tachometer HAC110 Speed Controller HVT12a Pendulums HVT12b Torsional Oscillation (Free and Damped) HVT12h HVT12c Mass Spring System Beam Bending (Transverse) Vibration There are also a wide range of other experiments available within our Vibrations range. Contact your local P.A. Hilton Ltd agent for more details. Page 2 of 7
Description HVT12 Standard Figure 1: HVT12 : A rectangular steel beam pivots at one end from a bracket and bearing attached to the HVT12f Vibration Frame. A spring is attached to the free end of the beam to enable the beam to vibrate. The horizontal position of the spring can be adjusted using the integral adjustment system Beam displacement is measured using an LVDT displacement transducer from the HAC90 Tachometer. The output signal from the LVDT can be displayed using the HVT12k data Acquisition system. The beam can vibrate freely by displacing the free end by a known amount between the two bump stops provided within the HVT12f Vibrations Frame. Alternatively the beam can be forced to vibrate using the Motor Exciter. The motor exciter has integral imbalanced masses, which when rotated excites the beam to vibrate. The speed of beam excitation is controlled using the HAC110 Speed Controller and its output monitored with the tachometer display HAC90 Tachometer. The output from the tachometer can also be fed into the HVT12k Data Acquisition System. A set of calibrated weights are supplied to vary the weight being vibrated. These weights attach to the underside of the motor exciter or in another position along the beam. The beam can be vibrated freely or forced. It can also vibrate with or without damping. Damping is introduced onto the beam using a set of damping discs and damping tank. The damping discs have adjustment which allows the amount of damping to be altered. Full technical instruction manual included detailing apparatus assembly, operation, theory and example results. Supplied as standard 1 Vibrations Frame (HVT12f) 1 Beam, pivot and spring (HVT12g) 1 Vibration Absorber (HVT12d) Data Acquisition System (HVT12k) 1 Interface, complete with Power Supply, USB Lead, Master Software CD 1 Tachometer (HAC90) 1 Speed Controller (HAC110) 1 Motor Exciter (HAC120) 1 Vertical Support 1 Dash pot Damper 1 LVDT Sensor 1 Basic Maintenance Kit & Instruction manual Page 3 of 7
Detailed Specification HVT12d Vibration Absorber HAC90 Tachometer Figure 2 HVT12d A central block is clamped to the test beam which carries two spring steel strips clamped in a cantilever arrangement transversely across the test beam. Attached onto each cantilever is a set of masses, which can have their magnitude and position adjusted. With the aid of the LVDT from the HAC90 the cantilevers and mass system can be tuned to the same natural frequency as the surround test beam and motor exciter. Once this is achieved the resonance frequency of the original system can be observed along with the resonance frequency of the vibration absorber itself. Figure 4 - HAC90 The exciter is controlled via the Speed Controller, and the excitation force frequency is displayed via the tachometer (pictured above). The spring resists the displacement of mass from its equilibrium position. An oil dashpot provides damping. The LVDT sensor records the amount of beam displacement. Both the LVDT signal and the excitation frequency signal are fed into the data acquisition system for computer linking and real-time data display and storage. This is an excellent visual demonstration of how a vibration absorber operates. Students can plot the resonance curve of the test beam with and without the damping absorber thus explaining fully its use. HVT12k Interface & Data Acquisition Software HAC110 Speed Controller Figure 3 - HVT12 interface This is a two channel digital oscilloscope, with USB connection to a host computer (Not supplied). The data acquisition software supplied allows the capture, display, storage and retrieval of the excitation frequency and beam response from the HVT12 apparatus. Figure 5 HAC110 The HAC110 makes up an essential control component of the HVT12 and connects directly to the HAC90 Tachometer, HAC120 Motor exciter and motor exciter of the HVT12c (sold as part of HVT12c experiment module). Its main purpose is to control the rotational speed of the motor exciters used on the HVT12c and HVT12g.
HAC120 Motor Exciter Figure 6 HAC120 Its primary function is to transmit rotational motion into linear displacement of a beam, and hence force the beam to vibrate at varying amplitudes and frequencies. The exciter motor is clamped onto a rectangular beam, in the desired position, i.e. onto the beam within the HVT12g, Free and Forced vibration. The exciter assembly houses two out of balance masses, which when rotated at speed, created a sinusoidal excitation. This excitation motion is transmitted to the test beam, which starts to vibrate. The frequency of vibration changes with the changing speed of the motor. The exciter motor is controlled by the speed control unit HAC110 and all the connection cables and sockets are factory fitted. A proximity sensor mounted to the rear of the motor gives the signal to the HAC90 Tachometer. Dimensions Frame Length 1380mm Frame Height 1500mm Frame Width 310mm Weight 18kg Internal Working area 1220 x 760mm Services Required Minimum Host Computer requirements Host Computer with the following specifications: Intel Pentium 3 or equivalent processor > 800MHz processor speed Microsoft Windows NT, 2000, ME, XP (end user must have operating system CD for XP and below) VGA Monitor capable of at least 16-bit colour at 800 x 600 resolution 150Mb space available on hard drive USB1.1 and USB2 for data acquisition connection. Powered USB port(s) if possible Ordering Information Order as: HVT12 Universal Vibrations Apparatus Optional Extras, Order as: Pendulum Experiment Torsional Oscillation (Free and Damped) Beam Bending (Transverse) Vibration Mass Spring System Language English HVT12a HVT12b HVT12c HVT12h Shipping Specification (Approx.) Net Weight: 59 kg Gross Weight: 149 kg Packing Case Dimensions: 158 x 127 x 94 cm Packing Case Volume: 1.88m 3 Also Available on Request Further detailed specification Additional copies of instruction manual Recommended list of spares for 5 years operation Page 5 of 7
Optional HVT12a Pendulum Experiment Optional HVT12b Torsional Oscillation (Free and Damped) Test set comprising the following three pendulums Compound Pendulum Centre of Percussion Bifilar/Trifilar Suspension Simple and Compound pendulums Radius of Gyration Fulcrum Position Acceleration due to Gravity Centre of Percussion ( sweet spot ) Moment of Inertia Order as: HVT12a HVT12f Vibrations Frame The HVT12b comprises a wire rod clamped to a frame mounted bracket, the rod having a solid disc that can be attached at variable positions. A solid ring is included, and rests onto the disc to increase its inertia. A support frame, damping cylinder and tank enable fixed and free end conditions to be created, and for controlled damping to be applied. Includes steel and brass rods complete with clamps and adaptors. To verify the dependence of the periodic time of oscillation of a "shaft mounted flywheel on the moment of inertia, length of shaft, and shaft diameter To determine the modulus of rigidity To study the effect of damping. Order as: HVT12b HVT12f Vibrations Frame Page 6 of 7
Optional HVT12c Beam Bending (Transverse) Vibrations Optional HVT12h Mass Spring System A flexible beam is supported between two end brackets which create simply supported end conditions. One end bracket allows pivoting only whilst the other allows rolling and pivoting only. One of the brackets is supported on vertical supports that can be moved depending on the beam length being used. The vertical brackets and standard length beam are both supplied. The beam is forced to vibrate using a motor exciter. This motor exciter can be attached anywhere along the beam length between the brackets The motor exciter supplied has the ability to have its mass increased by the addition of the calibrated masses supplied. These masses can also be attached in a stack at other points on the test beam. A damping tub, damping medium and damping discs are also supplied to give additional adjustment to the apparatus Order as: HVT12c Free vibration of a simply supported beam Forced vibration of a simply supported beam Natural frequency of oscillations Resonance Amplitude of vibrations Phase lag HVT12f Vibrations Frame HVT12d - Vibration Absorber HVT12k Data Acquisition System (Two Channel Digital oscilloscope) HAC90 Tachometer HAC110 Speed Controller An open helical spring is mounted inside the Vibrations Frame and free to vibrate vertically through a linear bearing guide. Loading is achieved through the use of various masses. Masses are added to the lower end of the spring to vary the frequency of oscillation. Frequency, periodic time and deflection can be measured. An upper adjustment system allows the springs vertical position to be varied and, thus its deflection increased and decreased. Free vibration Spring stiffness Periodic time HVT12f Vibrations Frame P.A.HILTON Ltd. Horsebridge Mill, King s Somborne, Stockbridge, Hampshire, SO20 6PX, England. Telephone: National (01794) 388382 International +44 1794 388382 Fax: National (01794) 388129 International +44 1794 388129 E-mail: Website: sales@p-a-hilton.co.uk www.p-a-hilton.co.uk Page 7 of 7