MANUAL

TERCO MT 3037

UNIVERSAL TESTING MACHINE

The Equipment

MT 3037 shown in Figure 1 is a universal testing machine capable of a wide range of tensile and compression test.

Figure 1: Terco MT3037 Universal Testing Machine

The machine is especially designed for teaching purpose, and it is very easy to handle. With the standard unit, tensile test can be performed on various metal test pieces as well as compression tests and hardness test according to Brinell.

Using different accessories, bending test, folding tests, shearing tests as well as deep-drawing tests can be carried out. The machine is fully automatic and the power is generated by a motor driveb hydraulic cylinder.

It can be controlled both manually or by computer. The speed of the cylinder can be manually adjusted to the requirement of the test. The powder is transferred extremely smoothly and with constant speed, thus giving best possible test results.

The power as well as the extension will be displayed on the monitor both as digital values and as bar diagrams.

After the test a complete diagram, with values sampled 4 times/sec is displayed both as diagram. The diagram can be printed out

How to get the equipment ready.

1:0 Check the equipment

- The MT 3037- Digital indicator- Signal cable to the dL indicator- 9 pin RS 322 cable to the PC- Main cable 5 pin 3 phase- Tool box.

1:1 Connect the main cable with main supply

1:2 Connect the PC cable and dL indicator cable in the contacts as shown in Figure 2.

Figure 2: MT3037 Instrument Panel

1:3 Start the Pump. Start the pump motor by pushing the main contact button on the side of the machine. It is black or

green. The red button is the off button.

1:4 Change of Phase Sequence.Please note that, if the pump in the machine does not work, the direction of the phase sequence must be changed.

This can easily be done with screw driver by twisting/ changing position of two pins as shown in Figure 3.

Figure 3: How to Change Phases

1:5 Put the left switch on the instrument panel to “ ON”

1:6 Switch on the dL-indicator.

1:7 Start the PC and enter the software program.

1:8 Install the program.

Start windows Insert Installation diskette. From Program Manager choose “ Run”. Type a:/Install and click OK.

When the installation window is shown on the screen, click “ install’. The program creates catalogues and copies files to the hard disk. The program also creates a new program manager “ TERCO MT 3037”.

1:9 Program Start.

Start Windows. Choose TERCO MT 3037 from the Program manager. Start the program with a double-click on the tensile test icon.

Click the measurement icon in the tool bar on top of the screen. A measuring window is shown on the screen. In the window, the powder and the expansion of the test piece is shown in digital mode as well as in analogue mode.

Max. Power

The pump is calibrated at the factory and will stop at 30 kN which is maximum.

When the equipment is used without computer, the power will be displayed on the instrument panel as a bar graph.

Speed adjustment value

The valve is very sensitive and a good testing speed is achieved by opening valve 1/16 of turn, anticlockwise (mechanical valve).

Instrumental panel

Includes besides the Pressure Indicator also the contacts OFF-ON, the meaning is obvious. MAN-PC to use the equipment through PC or to use it manually.

Up – Down

Up – Down, to control the direction of the cylinder. This can only be done in MAN-mode

LAB 2: TENSILE TESTING

The tensile test is one of the most important of all materials tests. The information from such a test is more accurate and gives more details on the strength of materials. It is especially suitable for steel of low carbon content (0.12 – 0.25%). Low carbon steel is the most important of construction steels and is used in the manufacture of cars, ships and bridges. Other materials can of course, be tensile tested on the tensile test machine.

Introduction :

Tensile testing is one of the most fundamental tests for engineering, and providesvaluable information about a material and its associated properties. These properties canbe used for design and analysis of engineering structures, and for developing newmaterials that better suit a specified use. Aim:To complete a tensile test on four different materials.

Objectives:1. To derive the modulus of elasticity, E for four different materials.2. To determine the stiffness, toughness, ductility, yield strength and ultimate tensile strength for

four different materials.

Apparatus:Terco MT3017 Universal Testing MachinePC with Terco MT3037 software installed.Dial indicatorFour different test pieces: i.e. mild steel, copper, brass and aluminium.

Procedures:1. Check the measurements of the test piece as required by the experiments.

2. Insert the test piece.2.1 Put the middle switch on the instrument panel on “Man”. 2.2 Use the right switch to vertically adjust the main cylinder, to be able to insert the test

piece. 2.3 The test piece should be pre-stressed by turning the upper part of the main cylinder

clockwise, or by tightening test piece holder.2.4 The pre-stress value should be about 1.0 kN.

3. Set the dL-indicator to Zero.3.1 Push the dL-indicator stop upwards, so it just touches the indicator tip. 3.2 As soon as the dL-indicator starts to show figures, the tip is reached. 3.3 Then press the button marked “origin” until the display shows 0000 only.

4. Put the middle control switch to “ PC” and go to the PC.4.1 Click Measurement and you will get a window with 0-15 kN and 0-30 kN.

4.2 Click your choice.4.3 Please note, that the machine is programmed to show 0 until the pressure is 1.5 kN. The

reason for this is residual pressure in the system that cannot be avoided. This does not harm the experimental value.

5. CLOSE THE PLASTIC SAFETY DOOR!5.1 The plastic safety door has a safety contact.5.2 If the does is not shut, the machine will not work!

6. START THE EXPERIMENT6.1 Click the start button on the Screen.6.2 The machine starts and the cylinder moves slowly upwards.6.3 Meanwhile, the measuring values are stored in a table with four measurements per sec.6.4 The table can hold maximum 300 measurements which correspond to 70 seconds

measuring time.6.5 If the test is performed too fast (or too slow), the speed can be adjusted by turning the

valve under the instrument panel.6.6 A normal test should take 25-30 seconds and will give 150-180 measurements.6.7 This is achieved by opening the valve 1/16 turn from closed position.

7. End of Test: When the test piece brakes, the power goes down very quickly and the machine stops automatically.

8. Table: After the test is finished, click “ table’ and the complete table is shown on the screen.

9. Diagram: In case you want a diagram, click the table icon, and the measuring values are transferred to a diagram. The diagram cab be maximised by using the maximise icon, according to the standard windows method.

10. Save: Only the table can be saved. 10.1 To activate the Table window, click the table window. A coloured title bar confirms

activation.10.2 Click the storing icon (look like a diskette)10.3 Choose a proper name.10.4 The file extension is always .tbl and does not need to be typed.10.5 Click OK and the table is stored.10.6 The table can be transferred to Microsoft Excel.

11. Open: Previously stored tables can be shown on the screen by clicking the “open” icon, and by choosing a file name.

12. Printing of Diagram: Click menu title “ graph’, Choose “ print graph”, and click OK. The printer will print the diagram.

13. Close the program: Click “File” and choose “ EXIT”. You have closed the program.

NOTE! 1. Measurement values can only be stored as table files but they cannot be printed.

2. Do not forget to switch off the dial gauge after the test, in order to save the battery.3. Some words are in Swedish due to the Swedish windows version we used. We hope this is

of no consequence.

Observation:Initial diameter of specimen, d1 = ________Initial gauge length of specimen, L1 = ________Initial cross-section area of specimen, A1 = ________Load of yield point, Ft = ________Ultimate load after specimen breaking, F = __________Final length after specimen breaking, L2 = _________Diameter of specimen at breaking place, d2 = ________Cross-section area at breaking place, A2 = ________

Calculation:Ultimate tensile strength = _______Percentage elongation % = ________Modulus of elasticity, E = ________Yield stress = _________% reduction in area = _________

Discussion

The test results were consistent for each of the materials, where each of the three stress-strain curves were approximately overlapping. An interesting observation can be made where sample one suddenly loses stress as it is stretched. This sample may have fractured partially across the cross section beforecomplete failure, or a void could have caused a sudden release of stress. All of the other samples exhibited consistent behavior. After the lab done, it is clear that the steel was the strongest material, followed by aluminum, copper and brass respectively. The data was consistent and that the testing procedure was valid and repeatable. The true fracture strength, shown gives a better view of the truestress at fracture. The steel had the highest true fracture strength, followed by the aluminum, copper and brass.Although the steel had a much higher modulus of elasticity (209300MPa, compared to 69460MPa for the 6061-T6 aluminum), and a higher ultimate tensilestrength, the yield strength is about the same as the 6061-T6. The higher ultimate stress isdue to work hardening as the material is plastically deformed. The introduction ofdislocations reduces their motion, and hardens the material. The 6061-T6 is a temperedand aged alloy that is already precipitation hardened. It will not work harden as much asthe A-36 steel, resulting in a lower ultimate tensile strength. The standard deviations forthe yield strength and modulus of elasticity are also small compared to the averagevalues, proving the consistency of the data.The modulus of resilience and the modulus of toughness are important values indetermining the energy that a material can absorb before yielding and before fracture.The modulus of resilience is the area under the engineering stress-strain curve up until the

yield, and corresponds to the energy per unit volume that a material can absorb before ityields. The 6061-T6 aluminum had the highest modulus of resilience, followed by A-36 13steel, polycarbonate, and PMMA. The aluminum had the highest resilience due to thehigh yield strength, and the low modulus of elasticity (compared to the A-36 steel), asshown in Table 3. The low modulus of elasticity ensured that the aluminum was strainedmore before yielding, allowing it to absorb more energy.The modulus of toughness was the highest for the A-36 steel due to the high ultimatetensile strength, and the ductility of the steel. The polycarbonate had a higher modulus oftoughness than the 6061-T6 aluminum due to its high ductility, even though it had alower yield and ultimate tensile strength. The acrylic had the lowest modulus oftoughness due to its brittle nature.The percent reduction of area and the percent elongation are indicators of the ductility ofa material. All of these values are located in Table 4. A more ductile material will have agreater percent elongation, and the material will neck down further, resulting in a greaterreduction of area. The A-36 steel samples had the greatest reduction of area due to thelarge amount of necking just before fracture. The polycarbonate had the highest percentelongation due to the straightening of the polymer chains. The polymer chains did notneck down after they were straightened, which resulted in a smaller percent reduction ofarea compared to the steel and aluminum samples. The aluminum did not elongate as faras the steel due to the alloying of the material and the precipitation hardening that wasused to improve other properties. The PMMA had the lowest percent reduction of areaand the lowest percent elongation, indicating that it is a brittle material.The true stress and true strain take into account the changing area of the cross section asit is being elongated, and the strains that accompany the changing area. Accounting forthese two effects results in a final true stress that is much higher than the engineeringfracture stress and a greater amount of strain. As shown in Figure 7, the true stressreaches a maximum at the point of fracture. At this point, the area is much smaller, so thespecimen cannot withstand a large load, which causes the engineering stress-strain curveto drop off after necking. There is no ultimate tensile stress in the true stress-strain curve14as with the engineering stress-strain curve, and the true stress is always increasing upuntil fracture.The Ramberg-Osgood model proved to be excellent at determining the true stress athigher values of true plastic strain, but had higher error at low values of true plasticstrain, especially near the yield strain, where plastic strain is essentially zero. Table 5shows that near the ultimate tensile strain, the error is very small, but near the yieldstrain, the error is rather high at 19.84%. The aluminum samples did not exhibit thepower hardening behavior that is typical of the Ramberg-Osgood model. The engineeringstress-strain curve was flat after yielding, and not curved like the model shows in Figure8. Since the model was fitted to the data between three times the yield strain, and theultimate tensile strain, it does not fit the sample well at low values of true plastic strain.This error could be alleviated by fitting multiple models to the curve, or by choosing adifferent model that better fits the shape of the engineering stress-strain curve. Questions:

1. What general information are obtained from tensile test regarding the properties of a material?A tensile test, also known as tension test, is probably the most fundamental type of mechanical test you can perform on material. Tensile tests are simple, relatively

inexpensive, and fully standardized. By pulling on something, you will very quickly determine how the material will react to forces being applied in tension. As the material is being pulled, you will find its strength along with how much it will elongate.

2. What kind of fracture has occurred in the tensile specimen and why?3. Which is the most ductile metal? How much is its elongation?

LAB 3: BRINELL TEST

The hardness of a material is defined as its capacity to withstand indentation from another body. There are many methods used in hardness testing and the results are difficult to compare as the indenting body and pressures applied are so unlike. The most common tests are Brinell, Vickers and Rockwell. The hardness of the material can be measured from the depth, size and shape of the indentation.

The hardness test that you will be performing is the Brinell test. A steel ball of diameter 2.5 mm, 5 mm or 10 mm is pressed into the surface of the material under a pressure of 1.25 to 30 kN. The load is sustained for a certain period, depending on material (steel – 15 s). The diameter of the indentation is measured using a measuring microscope. The Brinell hardness, HB is defined as load divided by the spherical indentation area according to equation (1) below:

(1)

Where HB = Brinell Harness numberD = diameter of the steel balld = diameter of the indentationP = applied load in kg

The Brinell test can be completed on soft and half hard materials. The indentation is relatively large.

Aim:To determine the hardness of four materials using Brinell test.

Objectives:1. To understand what hardness is, and how it can be used to indicate some properties of

materials.2. To conduct typical engineering hardness test and be able to recognize commonly used

hardness scales and numbers.3. To be able to understand the correlation between hardness number and the properties of

materials.4. To learn the advantages and limitations of the common hardness test methods.

Apparatus:Terco MT3017 Universal Testing MachineBrinell test setFour different test pieces: i.e. mild steel, copper, brass and aluminium.

Procedures:1. Put in the Brinell anvil in the test machine.

1.1 Put the test piece in place on the Brinell anvil.1.2 It is important that the distance of the indentation from edge of the test piece is 2,5 times

the indentation diameter.

2. Close the plastic door.3. Adjust the switches.

3.1 Put the left switch on the Instrument Panel to ON.3.2 Put the middle switch to MAN.

4. Adjust the speed.4.1 Turn the speed adjustment valve 1/8 of a turn anticlockwise.4.2 This will increase the speed of the main cylinder.

5. Start the experiment.5.1 Push the left switch to down and hold it there during the test.5.2 The indentor will reach the Test piece and start the indention.5.3 The indention will reach a maximum of 30 kN.5.4 The equipment has been pre-calibrated to 30 kN in the factory.5.5 Let the indention have a duration of 15 sec.

6. Finish the experiment.6.1 Push the left switch to up, enough to release the test piece. 6.2 Open the plastic safety door and take out the test piece.

7. Check the result.7.1 Use the magnifier to check the diameter of the indention.7.2 The hardness is identified as N/mm2.7.3 The applied force divided with the surface of the indention.

Questions:

1. Why do the instructions specify the period during which the pressure is to remain on the Brinell ball?

2. Is the Brinell indentation truly spherical? Explain.3. In a Brinell test why is a polished specimen surface more important for harder

materials?4. Will side bulging resulting from a Brinell impression taken too close to the edge of a

specimen result in a hardness number greater or less than the value obtained by a correct procedure?

5. Why is a minimum thickness of at least ten times the depth of the impression required in the Brinell test? How should the value obtained be influenced by specimens, which are too thin assuming they are tested on a heavy anvil, which is:

(a) Harder than the specimen?(b) Softer than the specimen?

6. Is a hardness test normally employed because the property of hardness is desired? Explain.

7. Can a satisfactory comparison of two dissimilar materials be obtained from hardness numbers?