CE335 - Lab Manual #3 Impact test

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Purdue University *

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335

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Civil Engineering

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Oct 30, 2023

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Impact test CE335: Civil Engineering Materials Lyles School of Civil Engineering, Purdue University 1. Purpose: Impact Test Lab #3, CE335: Civil Engineering Materials Impact testing can be applied in order to study the behavior of a given material over a range of temperature. In addition, the result of the test which is a qualitative index of a materi al’s ability to resist extreme conditions can be used to compare the behavior of different materials or different alloys of a metal. The objectives of this laboratory experiment can be categorized as the followings: a. Objective 1: Students should be able to discuss the behavior of different materials (nylon, polyethylene and aluminum) under impact loading. b. Objective 2: Students should be able to discuss the effect of temperature on the impact resistance of metals. c. Objective 3: Students should be able to identify the temperature-dependent ductile-brittle transition. d. Objective 4: Students should be able to discuss the difference between different methods available to study the impact energy of materials. e. Objective 5: Students should be able to understand the difference between brittle and ductile fracture, and how the energy absorbed in each differs 2. Scope: Generally, impact testing machine is used to study the materials’ ability to resist sudden impact. The result is the impact resistance or alternatively it is the amount of energy absorbed by the sample until failure. In this experiment, Charpy impact testing machine will be used to study the behavior of different materials over a range of temperature. 3. Definitions & Process Terminology: N/A 4. Lab Equipment to be used: Impact Testing Machine: An Impact Testing Machine is required to determine the amount of energy absorbed by a material during fracture and to study temperature-dependent ductile-brittle transition. For the purpose of this lab, the Charpy impact test, also known as the Charpy V-notch test will be used.

Impact test CE335: Civil Engineering Materials Lyles School of Civil Engineering, Purdue University Heater and Cooler: Since Impact test is done in different temperature, a device is required to either increase or decrease the specimens’ temperature. In this study, boiled water will be used to increase the specimens’ temperature while ice will be used to decrease the temperature. 5. ASTM, ISO Standard (if applicable): • ASTM D6110 – 10; Standard Test Method for Determining the Charpy Impact Resistance of Notched Specimens of Plastics • ASTM E23 −12c; Standard Test Methods for Notched Bar Impact Testing of Metallic Materials • EN 10045-1; Charpy Impact Test on Metallic Materials - Part 1: Test Method (V- and U- Notches) • ISO 148-1; Metallic materials — Charpy pendulum impact test — Part 1: Test method - Second Edition • ASTM E2248 – 12; Standard Test Method for Impact Testing of Miniaturized Charpy V-Notch Specimens • ASTM E23 REV A RUSSIAN; Standard Test Methods for Notched Bar Impact Testing of Metallic Materials 6. Lab Procedure a. Background/theory Tensile and compression tests yield information about the material properties which can be used for design purposes. However, they do not generally subject the materials to extreme conditions such as low temperature, stress concentrations, extra loading and high strain rates. Impact loading is the high force or shock applied in a short time which simulates the extreme loading conditions. The test gives a qualitative index of a material’s ability to resist extreme conditions. Impact is a very important phenomenon in governing the life of a structure. For example, in the case of an aircraft, impact can take place by a bird hitting a plane while it is cruising, or during take-off and landing the aircraft may be struck by debris present on the runway, and as well as other causes. Two common impact tests are the Charpy test and the Izod test. In both, the specimen is a small beam of the material with a notch machined into one side and is loaded by the impact of a

Impact test CE335: Civil Engineering Materials Lyles School of Civil Engineering, Purdue University swinging pendulum. The Izod impact test differs from the Charpy impact test in that the specimen is held in a cantilevered beam configuration as opposed to a three-point bending configuration. Figure 1 represents the loading type for Charpy and Izod testing methods. The Charpy test was developed around 1900 by S. B. Russell (1898, American) and G. Charpy (1901, French). In the early 1900s, the test became known as the Charpy test due to the technical contributions and standardization efforts by Georges Charpy. Today it is used in many industries for testing materials used in the construction of pressure vessels and bridges and to determine how storms will affect materials used in them. Izod impact testing is named after the English engineer Edwin Gilbert Izod (1876 – 1946), who described it in his 1903 address to the British Association, subsequently published in Engineering. Specimen types include notch configurations such as V-notch, U-notch, and Key-Hole notch. Figure 2 exhibits v-notch specimen which is going to be used in our experiment. Figures 3 and 4 show apparatus for doing this experiment. The machine is digital and automatically calculates the energy absorption of specimens. Figure.1. Charpy and Izod loading types Figure 2. V-notch specimen

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Impact test CE335: Civil Engineering Materials Lyles School of Civil Engineering, Purdue University Figure 3. Machine for Dynamic Impact test Figure.4. Hammer and the place for putting specimen The impact will cause the specimen to fail more or less on a plane through the notch. An arm held at a specific height (constant potential energy derived from its mass and the initial height Hammer Specimen is placed here

Impact test CE335: Civil Engineering Materials Lyles School of Civil Engineering, Purdue University above the specimen) is released. The arm hits the sample and breaks it. Variables including the size and shape of the specimen and notch, the orientation at which the specimen is impacted, and the range of speeds at which the bar is impacted are specified so that test results will always be comparable. From the energy absorbed by the sample, its impact energy is determined. The more energy absorbed, the better the material to resist extraordinary loadings and conditions. The test results can be used for two main purposes: (a) to compare the behavior of different materials, or different alloys of a metal; (b) to study the behavior of a material at different temperatures. The fracture planes of materials are shown in Figure 5 and 6. Some materials have a significant temperature dependence of their properties over the range of temperatures usually encountered by their application. For instance, materials with a body center cubic (BCC) structure such as iron show a dramatic temperature dependence. This temperature dependence is of great importance in the use of steel in construction. Face center cubic (FCC) structures such as aluminum do not have the same behavior. Figure 7 represents a schematic temperature dependent behavior of a material. It can be seen that the behavior of material can be brittle, ductile, or a combination of these two.

Impact test CE335: Civil Engineering Materials Lyles School of Civil Engineering, Purdue University Figure.6. Comparison of fracture surface of all specimens (room temperature) Why fracture surface of aluminum is different from the Polyethylene and Nylon

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Impact test CE335: Civil Engineering Materials Lyles School of Civil Engineering, Purdue University Figure.7. A schematic temperature-dependent behavior b. Experiments to be performed: In this experiment, students will test different Charpy specimens over a temperature range. Three different materials including polyethylene, nylon, and aluminum will be tested at freezing, room and hot temperature. c. Measurements to be taken by students: Thickness and height of each material should be measured in order to be used as an input for the Charpy testing machine. In addition, students are required to record the value of absorbed energy for each specimen. d. Information given to the student prior to the lab: N/A e. Description of the specimens. In this experiment, standard V-notched Charpy specimens will be used based on ASTM E23. f. Check list i. Before the lab session: Attend Lab preparation. ii. Before test: N/A. iii. During test: Record absorbed energy values for each specimen

Impact test CE335: Civil Engineering Materials Lyles School of Civil Engineering, Purdue University iv. After test: Summarize the test results and your observations from the experiment using a table shown below. Temperature (ᵒC) Impact energy (J) Nylon Polyethylene Aluminum • Plot showing the variation of impact energy with the temperature for the three materials. • Discussions a) Discuss the Advantages and Disadvantages of Impact Test. b) Indicate transition temperature range c) Discuss about the effect of temperature on the behaviour of the three materials and comment on the differences of material properties. d) Discuss about possible errors in the measurements. g. Expected outcome of the experiments: Students should be able to discuss the application of this experiment in real life projects. In addition, they should be able to explain the two different impact testing methods including Charpy and Izod testing methods. The measured values have many applications in engineering fields. Students are highly required to be able to discuss these applications. 7. Safety: N/A 8. References: [1] R.C. Hibbeler, Mechanics of Materials, Prentice Hall, 2011. [2] Charpy impact testing, http://en.wikipedia.org/wiki/Charpy_impact_test [Accessed March25, 2013]

Impact test CE335: Civil Engineering Materials Lyles School of Civil Engineering, Purdue University [3] Izod impact testing, http://en.wikipedia.org/wiki/Izod_impact_strength_test [Accessed March25, 2013] [4] Digital image correlation, http://en.wikipedia.org/wiki/Digital_image_correlation [Accessed Feb 10, 2013] 9. Preferred media: The lab materials are in the Purdue Brightspace system. 10. Revision history : a. Revision 1, P. Zavattieri and A. Behnood, Monday Mar.18, 2013, Created the file. b. Revision 2, P. Zavattieri and M. Shishehbor, Friday Dec. 13, 2013, Modified the file. c. Revision 3, P. Zavattieri and Y. Chiu, Monday, Mar. 24, 2014, Modified the file d. Revision 4, C. Moro, September, 2021, Adaptation to new course CE 335 (and Brightspace).

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