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Static and dynamic Balance

Description:

This product allows students to do experiments in balancing a rotating mass system and check their results against accepted theory. A sturdy base unit holds a test assembly on four flexible mounts. The test assembly includes a balanced steel shaft mounted horizontally on low friction bearings. The equipment includes a set of four rotating masses (balance blocks). The balance blocks fix in any horizontal position and relative angle on the shaft. Each block contains a different (and removable) circular insert, allowing students to create four blocks of different mass and moment. Without the inserts, the blocks become four identical masses for simple balancing tests. Students fit an extension shaft and pulley (supplied) to the end of the balance shaft. They then add weights (supplied) to a cord wound round the pulley to measure accurately the moment of each balance block. The test assembly includes a protractor at the end of the shaft and a linear scale with slider under the shaft. These allow accurate measurement of balance block angles and horizontal positions. An electric motor and belt turns the shaft to test for dynamic balancing. The flexible mounts allow the assembly to vibrate, showing imbalance during dynamic balancing tests. Students remove the belt to check for static balance (the shaft should remain static at any angular position). A transparent safety dome covers the whole rotating assembly. An interlock shuts off power to the motor when the dome is not fitted.

Learning Objective:

Explanation and determination of unbalance

Investigation of static, dynamic and basic unbalance

Balancing process

Device component:

Steel Shaft

Electric motor

Weights

Charpy impact

Description:

In the field of industrial quality control, the impact test is a widely used test method with which to quickly and easily determine characteristics for a material or component analysis. This  experimental unit is a solid-pendulum impact tester that designed for the Charpy notched-bar impact test. The clean layout and simple operation mean the experimental sequence can be observed in all details and phases. In the experiment, the hammer attached to a pendulum arm describes an arc. At the lowest point of the hammer path, the hammer transfers part of its kinetic energy to the notched specimen. The specimen is either destroyed or bent by the impact and pushed between the supports. The notched-bar impact work required to deform the specimen is read directly off a large scale. In order to vary the output energy, the mass of the hammer can be changed by adding or removing weights. A brake reduces the residual energy of the hammer on each swing until it reaches zero. A protective ring ensures the experiments can be conducted safely while also fixing the hammer in place. The hammer is triggered with two hands for safer operation. A protective cover the operating area is available as an accessory. The experimental results allow quality control and an analysis of the fracture behaviour of different metallic materials. Non-metallic specimens can also be used. Specimens with different notch geometries, in different materials and specimen dimensions are included in the scope of delivery.

Learning Objective:

Determine the notched-bar impact work

Determine the notched-bar impact strength

Analyse the fracture surface characteristics

Plot a notched-bar impact work–temperature diagram

Influence of notch shape, material and specimen temperature on the notchedbar impact work

Device component:

Hammer with removable additional weights

Notched bar impact specimens

Hammer fixing

Weights

Creep test

Description:

Components that are subjected to long-term constant loads deform plastically. This material behaviour is called creep. The creep rupture test is a destructive test method for determining the material behaviour (creep) at constant test temperature (room temperature and below) and after prolonged exposure to a constant load. This  experimental unit demonstrates typical phenomena such as phases of different creep rates or temperature- dependent creep behaviour. The clean layout and simple operation mean the experimental sequence can be observed in all details and phases. Lead and plastic specimens are used in order to achieve acceptable creep rates at room temperature. Experiments can also be conducted below room temperature by means of a transparent temperature-controlled box with storage elements. In the experiment, the specimen is subjected to a constant tensile load at a given, constant temperature. The tensile load is generated by a lever and stepped weights. The specimen holders are equipped with knife-edge bearings to avoid bending stresses on the specimen. An adjustable stop protects the dial gauge at fracture of the specimen and prevents the loads impacting the experimental unit. The elongation of the specimen over time is recorded by a dial gauge and a stopwatch and represented in a strain–time diagram as the so-called creep curve.

Learning Objective:

- creep in specimens of various materials

- record a strain–time diagram (creep curve)

- Influence of temperature and load on the creep

- Load and recovery in plastics

Device component:

Specimens

Weights

Lever

Thermometer

Storage element for cooling the specimen