CON 251 Lab Notebook

Semester

Section

Name

Name

Total Points

CON 251 Lab #1

Measurements Lab Activity

Introduction

This lab activity is to familiarize students with a variety of measurement methods and measuring instruments that are used for testing. Students will use the following measuring devices for this lab activity:

Tape Measure

Ruler

Dial caliper

Digital caliper

Micrometer

Thread pitch gage

Protractor

Triple beam scale

Pin gages

Procedure:

This lab activity has ten different stations that require measurements and or calculations that need to be collected. Start at any station and complete the activity then move to the next open station. When measurements have been taken at all stations each group will need to complete the calculations or summaries away from the stations so others can gain access. When the lab is completed, keep the report and add it to your workbook.

Sample #1

Measure the length of the 2X4 to the nearest 1/16”

Length

Sample #2

Using a dial caliper, measure the diameter and length of the round piece of aluminum to the nearest .001”.

Diameter

Length

Cross Sectional area

Volume

Sample #3

Using a digital caliper, measure the diameter, inside (ID) and outside (OD) and the length of the aluminum tube to the nearest .001”.

Diameter (OD)

Diameter (ID)

Length

Cross Sectional Area of the aluminum only

Volume

Sample #4

Using a Digital Caliper, what is the length and width of the rectangular pocket (measure to the nearest .001”) ?

Length Width

Sample #5

Using a steel rule, what is the length and width of this blue aluminum plate to the nearest 1/16” ?

Length

Width

Sample #6

Using a digital caliper, what is the depth and width of the blue groove in this part to the nearest .001”?

Depth

Width

Sample #7

Using a steel rule and thread pitch gage, what is the nominal diameter and the thread pitch of this bolt? (nominal) diameters of fasteners are measured in 1/16” fractions.)

Bolt Diameter

Threads per inch (thread pitch gage)

Sample #8

Using a micrometer, measure the width and thickness of the square tool to the nearest .001”.

Width

Thickness

Sample #9

Using pin gages, determine the diameter of holes A, B, & C.

Diameter A

Diameter B

Diameter C

Sample #10

Using a Digital caliper, measure the width and thickness of this block. Also measure the diameter of the round hole and the length of the slot above the hole to the nearest .001”.

Width

Thickness

Diameter of the hole

Length of the slot

Sample #11

Using the adjustable protractor, measure all three angles to the nearest degree.

Angle A

Angle B

Angle C

Sample #12

Using the test procedure provided on the last following page to calculate the Relative Density of samples A, B, and C.

A

B

C

Relative Density

ASTM D-792

Density= A -B

(A-B) - (C-D)

Where:

A = mass of the specimen +Wire in Air

B=mass of wire in air (.58 g)

C=mass of wire & specimen immersed in water

D=mass of wire with end immersed in water (.54 g)

Sample A mass in air (A)

Sample A mass in water (C)

Sample A Relative Density

Sample B mass in air (A)

Sample B mass in water (C)

Sample B Relative Density

Sample C mass in air (A)

Sample C mass in water (C)

Sample C Relative Density

CON 251 Lab #2

Metallic Tensile Testing Lab Activity

Introduction:

The tensile test is a common test performed on metals, wood, plastics, and most other materials. Tensile loads are those that tend to pull the specimen apart, putting the specimen in tension. They can be performed on any specimen of known cross-sectional area and gage length to which a uniform tensile load can be applied.

Tensile tests are used to determine the mechanical behavior of materials under static, axial tensile, or stretch loading. Data and calculations for these tests include tensile stress, tensile strength, elastic limit, percent elongation, modulus of elasticity, proportional limit, percent reduction in area, yield point, yield strength, and similar properties.

ASTM standards for common tensile tests may be found in sections E8 (metals), D638 (plastics), D2343 (fibers), D897 (adhesives), D987 (paper), and D412 (rubber).

Tensile Testing – Procedure:

Tensile tests are used to determine the tensile properties of a material, including the tensile strength.

In order to conduct a tensile test, the proper specimen must be obtained. This specimen should conform to ASTM standards for size and features. Prior to the test, the cross-sectional area may be calculated and a pre-determined

gage length marked on the specimen (usually 2”). This gage length is used to determine the amount of elongation that has taken place on the test specimen. The specimen is then loaded into a machine set up for tensile loads and placed in the proper grippers. Once loaded, the machine can then be used to apply a steady, continuous tensile load.

Data is collected at pre-determined points or increments during the test. Depending on the material and specimen being tested, data points may be more or less frequent. Data include the applied load and change in gage length. The load is generally read from the machine panel in pounds or kilograms. The change in gage length is determined using an extensometer. An extensometer is firmly fixed to the machine or specimen and relates the amount of deformation or deflection over the gage length during a test.

While paying close attention to the readings, data points are collected until the material starts to yield significantly. This can be seen when deformation continues without having to increase the applied load. Once this begins, the extensometer is removed and loading continued until failure. Ultimate tensile strength and rupture strength can be calculated from this latter loading.

Once data have been collected, the tensile stress developed and the resultant strain can be calculated. Stress is calculated based on the applied load and cross-sectional area. Strain is the change in length divided by the original length.

Principal properties determined through tensile testing include yield strength, tensile strength, ductility (based on the percent elongation and percent reduction in area), modulus of elasticity, and visual characteristics of the fracture. For brittle materials, which do not show a marked yield or ductility, data is collected for tensile strength and type and condition of fracture.

Expected Results

The results of tensile testing can be used to plot a stress-strain curve that illustrates the tensile properties of the material. Stress (in pounds per square inch or Pascal’s) is plotted on the vertical axis while strain (inches per inch, millimeters per millimeter, or unit less) is plotted along the horizontal.

As the load is applied, the curve is proportional and this period of linearity is termed the elastic region. Once the curve deviates from a straight line and begins to yield, the material has reached the proportional limit. Once the material has yielded, it exhibits plastic behavior or plasticity. Brittle materials do not exhibit much yield and are, therefore, less curved than ductile materials. Ductile material curves have marked areas of yield and curvature illustrates the degree of ductility. At the top of the curve is the ultimate tensile strength of the material. Once the curve has peaked, stress continues to decline while strain continues to increase. This condition continues until failure.

As with any testing situation, please observe caution and wear proper safety equipment.

Text References:

Chapter 14 – Tensile Testing

Appendix 2C pg. 479

Also see pages 474 & 475 for Stress Strain curves

CON 251 Lab #2

Tensile Testing Data

Sample # 1

*Thickness

*Width

*Peak Load lbs.

**Load at Yieldlbs.

*Peak Load at Rupture lbs.

* Measured or observed values

** Interpreted from Plot

(Ultimate Tensile strength )

σ =Load at Peak = psi

Cross Sectional Area

(Strain at Peak load)

Strain* =

Strain* = (final length – starting length)/ starting length

*At peak load

(Modulus of Elasticity)

Modulus of Elasticity = Stress/ Strain

Percent Elongation =

Per Cent Elongation = final length*- starting length X 100

Starting length

* final length after break

Sample # 2

*Thickness

*Width

*Peak Load lbs.

**Load at Yieldlbs.

*Peak Load at Rupture lbs.

* Measured or observed values

** Interpreted from Plot

(Ultimate Tensile strength )

σ =Load at Peak = psi

Cross Sectional Area

(Strain at Peak load)

Strain* =

Strain* = (final length – starting length)/ starting length

*At peak load

Modulus of Elasticity

Modulus of Elasticity = Stress/ Strain

Percent Elongation =

Per Cent Elongation = final length*- starting length X 100

Starting length

*final length after break

Problem:

We want to use #3 rebar to pre-stress a concrete beam.

How much load must be applied to the rebar to stress it to 80 % of its ultimate tensile strength?

Procedure:

  1. Reduce a middle section of the rebar sample on the engine lathe. (Turn until cleaned up)
  1. Measure the smallest diameter of the turned area.
  1. Using the Vega Tester, apply a load until the sample ruptures.
  1. Calculate the ultimate Tensile Strength
  1. Use a value of 80% of the calculated ultimate tensile strength to determine pre-stress value.
  1. Use a value of 80% of peak load to approximate pre-stress load.

Turned Diameter Cross Sectional Area

Load at Rupture lbs.

Ultimate Tensile Strength psi.

( Ultimate Tensile Stress = Load at Rupture / Area )

Pre-stress Load lbs.

(80% of load at Rupture)

Pre-stress value psi.

(80% of Ultimate Tensile Stress)

CON 251 Lab #3

Hardness Testing Heat and Treatment of Steel

Introduction (Chapter reference Chapter’s 4 & 19)

One of the most desirable characteristics of steels is the ability to easily change the hardness and strength the material. This process of changing the hardness is referred to as heat treatment. Steels are classified as carbon steels, alloy steels or special steels. This activity will focus only on carbon steels.

The classifications of steels was established by the Society of Automotive Engineers (SAE) and later adopted by the American Iron and Steel Institute (AISI) and is now referred to as the SAE-AISI system of steel classification.

Carbon steel is an alloy of iron and carbon, without significant amounts of other elements. Therefore the carbon content plays the most important role in determining the properties of carbon steel. About 85% of all steel is carbon steel. About 130 different grades of carbon steel are produced today to meet the growing needs of modern technology. Carbon steels are classified as low carbon, medium carbon or high carbon steels. The amount of carbon content determines which classification the steel is in. Low carbon steels contain between 0.08% and 0.35% carbon. In terms of tonnage produced, low carbon steels constitute the larges volumes with the extensive use as structural members in buildings and bridges. These steels can be easily welded, formed and forged, but have poor machining properties. Due to their low carbon content cannot be hardened through conventional heat treatment. Medium carbon steels are those with carbon content between 0.35% and 0.50%. Because of relatively high carbon content, these steels can be hardened by water quench and tempered. Medium carbon steels are considered the most versatile of all carbon steels because they can be hardened, easily welded and machined. High carbon steels are those with carbon content over 0.55%. The outstanding characteristics of these steels are that they can be heat treated more readily than any other carbon steels. However, because of the high carbon content these steels are relatively difficult to machine, form and weld. They are used for springs, hand tools, cutting tools and agricultural implements such as plow shears and cultivating shoes.

OBJECTIVES: To introduce those solid-state transformations of materialstructures, known as “heat-treatments”. More specifically, define “heat treating” as the controlled heating and cooling of metal alloys in the solid-state. The process starts by heating the steel above its critical temperature or austenitic temperature range. (Between 1333F and 1666F), which transforms the iron into austenite . The slow cooling of steel from its critical temperature over several hours or days is called “Annealing”. Annealing leaves the steel in its softest possible condition with the least amount of internal stress and maximum malleability. “Normalizing” involves heating the metal into its critical temperature then letting it cool in still air at room temperature. Normalizing forms even grain size that makes them easier to machine. “Quenching” is the process used to harden steel through out (through hardening) and is performed by heating the metal into its critical temperature then rapidly cool it back to room temperature. This rapid cooling causes the austenite to form into “Martensite” which is very hard and brittle. This will form the hardest and highest strength steel but is extremely brittle and has a high amount of internal stress. Depending on the carbon and alloying content, different quenching media are used. The most common media are, water, brine (salt water), oil and air. Water or brine provides the most rapid quenching. Oil is slower than water with air quenching being the slowest. “Tempering” is also referred to as drawing, is a process by which a hardened part is reheated to 400F to 800F and quenched in water. This process will relieve stress, reduce hardness and increase toughness of the processed part. “Case hardening” is also referred to as surface hardening and is used on such parts as gear teeth, axles and other parts and tools. These case hardened parts represent a compromise between the hard, wear resistant brittleness of high carbon steels and the softer, more ductile, less wear resistant low carbon steels.

The purpose of this lab activity is to familiarize the student with the terminology and methods used for steel classification and heat treatment. The lab activity will involve hardening, annealing, case hardening, tempering and Rockwell hardness testing.

Procedure: You must wear safety glasses for this lab

  1. Each group will get one sample each of O-1 tool steel 5/16” X3” round and 5/16”X3” round 1018 Cold Rolled Steel (CRS).
  2. Using the Rockwell hardness tester, measure the hardness of each sample. (take two readings for accuracy and record)
  3. Using the oxy-acetylene torch heat approximately 1” of each sample until it is orange, then quench quickly in water. (Use pliers to hold samples)
  4. Bead blast the ends of the samples that were hardened. This will remove oxides and scale from the samples.
  5. Repeat step 2. Making measurements in the middle of the hardened section. (take two readings for accuracy and record)

CON 251 Lab#3

Heat Treatment and Hardness Testing Data

5/16” Round O-1 untreated RC

5/16” Round O-1 hardenedRC

5/16” Round O-1 tempered RC

5/16” Round *CRS untreated RC

5/16” Round *CRS hardened RC

* Note CRS stands for Cold Rolled Steel

Briefly explain what occurred when a sample of O-1 was hardened and then held in a vise and hit with a hammer.

Briefly explain the advantages and disadvantages of through hardening and Case hardening.

CON 251 Lab #4

Masonry Screw Anchors Testing Lab Activity

Introduction:

Fasteners are a essential component used in the construction industry for connecting a variety of hardware or accessories to rigid structures such as walls, stone or brick. There are numerous fastening devices and systems that are used for numerous different applications. With so many choices, it is often times difficult to determine what fastener is best suited for a particular application. In many instances specifications and or callouts will specify precisely what fastener must be used. Most of the time a sub-contractor will use what is most familiar to him or her or what can be purchased at the best price.

The application that we will examine is that of the holding strength of a variety of different screw anchors. Two types of loading can occur with a screw anchor mounted on a vertical wall. The first is downward shear caused by the loading similar to a shelf bracket screwed to a wall. As loads are placed on the shelf, the downward force creates a downward shear between the bracket holding the shelf and the wall. The second is the pullout force applied as a result of the cantilever of the bracket pulling away from the wall. While both forces are at issue, most concern is usually with the forces applied from the cantilever more than the downward shear. This is because the shear forces are the greatest closest to wall and will increase the force on the cantilever as the load moves further from the wall. The tests will be conducted using #10 or 3/16” diameter fasteners. Typically wood screws, sheet metal screws and machine screws are used for these applications, depending on the type of anchors used.

Procedure:

Each group will test two different screw anchors. Holes will be drill according to the diameter specified for that type of anchor. Location of the holes is centered on the edge of the brick and 2-3/4” in from either end. Both edges of the brick will need to be drilled. One edge of the brick will be used to test the shear strength of the fastener and anchor. The other edge will be used to test the pullout force necessary to dislodge the fastener and anchor from the brick. This test will emulate a cantilever load being applied to the fastener and anchor. The pullout force test will be performed on the AST digital tester located in the metrology lab. The shear tests will be performed on the Testmark Compression Testing machine. The instructor will demonstrate both testing machines and procedures.