Structures and Properties of Materials Quiz

The amount of force exerted over a unit area. A force is considered applied when it is used to deform or distort a sample.

The change in length of a material in response to an applied force, calculated as the ratio of change in length to the original length.

The ability of a material to deform under stress and return to its original shape once the stress is removed. The material behaves like a spring.

Deformation that remains even after the stress is removed. The material permanently changes shape.

The point on the stress-strain curve where the material transitions from elastic to plastic behavior. Beyond this point, the material will not return to its original shape.

The maximum amount of stress a material can withstand before it breaks or fractures.

It is the ratio of stress to strain within the elastic limit. It's a material's ability to resist deformation under stress. Think of stiffness as how much a material resists bending or stretching.

The ability of a material to absorb energy before it fractures.

An electrical device that converts linear motion into an electrical signal. It measures small movements or deformations of a test specimen.

The sensitivity of LVDTs can vary from 0.003 to 0.25 V/mm.

The core is moved within the shell, which contains a primary coil and two secondary coils. The movement of the core changes the output voltage, and the relationship between core position and voltage represents the LVDT's characteristic response.

A graph that shows the relationship between the linear displacement of the core and the output voltage.

An electrical device used to measure tiny deformations (strain) of a specimen.

A device that measures the amount of force applied to an object.

The change in electrical resistance of a strain gauge is directly proportional to the deformation of the test specimen.

Strain gauges consist of foil or wire bonded to a thin base, typically made of plastic or paper.

When a strain gauge is stretched or compressed, its electrical resistance changes, which is proportional to the strain.

A measure of how much a strain gauge's resistance changes in relation to the strain applied to it.

The strain gauge is glued to the surface where the strain needs to be measured.

The deformation of the test specimen is transferred to the strain gauge due to the bonding between them.

The strain gauge deforms along with the surface, changing its resistance.

The increase in length of a strain gauge leads to an increase in its electrical resistance.

A Wheatstone bridge circuit is used to measure the small changes in resistance of a strain gauge.

A mechanical device that uses a dial to measure displacement or deformation.

Strain gauges are small, precise, and can measure both static and dynamic loads.

Dial gauges are simple to use, inexpensive, and can be used multiple times.

Strain gauges require extra devices for readout and are more expensive.

Dial gauges are large, have limited magnification, and only measure static loads.

The primary goal of all testing devices is to establish the relationship between applied load and the resulting deformation of a material. This information is crucial for calculating the material's mechanical properties.

A testing machine is a specialized device used to apply a controlled load to a test specimen and accurately measure the applied force.

A dial gauge is a mechanical instrument used to measure small linear displacements or dimensional variations in a workpiece. It works by amplifying the movement of a plunger through a gear system, translating it to a rotating pointer on a graduated dial.

An extensometer is a device specifically designed to measure changes in the length of a material undergoing a tensile test. It helps determine stress-strain relationships during deformation.

Testing machines are categorized based on the type of load they apply. Common types include Tension-Compression machines for pulling or pushing forces, Bending machines for flexing materials, and others for specific applications.

A Load Cell is a transducer that converts applied force into an electrical signal, allowing for precise and accurate measurement. It acts as a sensor to quantify the force exerted by a testing machine on the specimen.

A Data Acquisition System (DAS) is a system that collects and processes data generated by sensors like load cells and extensometers. It digitizes and stores the measurements, providing a record of the test results for analysis.

The dial gauge operates by converting the linear movement of a plunger into a rotating pointer movement, using gears and a system of springs. The pointer's position on the graduated dial indicates the measured displacement.

Strain gauges are attached to a load cell's internal member and are subjected to either axial loading or bending. When a voltage is input, the load cell produces an output voltage, which is measured using a digital meter.

Data acquisition is the process of collecting, transforming, and transferring data from sources to a processing system for display, analysis, and storage.

A data acquisition system is a combination of hardware and software that enables the measurement and control of physical characteristics in the real world.

Analog signals are continuous electrical signals, while digital signals are non-continuous.

Calibration ensures that the readings from a testing machine accurately reflect the load applied to the specimen.

You can calibrate testing machines by placing a load cell in the specimen position and measuring the output.