Charpy and Flextural Test - Report Example

HАRРY АND FLЕХURАL TEST Name: Student Reg No.: University: Course: Lecturer: Date of Submission: 3.6.2 Gypflax and control (mixed with 10% of sand) Samples Using the earlier Gypflax and gypsum samples, we repeated the steps that were done, but we reduced the total Gypsum by 10% and instead added an equivalent amount of sand of 10%. Using the dry Gypsum in the bowl, we then mixed it and left for two minutes to settle then we added some water that had been calculated into the bowl to dry the mixture. However, we noticed that a mix of sand and Gypsum solidifies faster when compared to Gypsum only. Thus, it is advisable to pour the mixture in the mould faster since it hardens faster to ensure that it settles inside the mould. The same steps and procedures are repeated for Gypflax samples, however, 4% of flax dust added with the Gypsum sand to the dry mixture. 4.2.2 Experimental results Five samples of Gypsum, Gypflax, Gypsum with sand and Gypflax with sand were tested and the results regarding the Maximum load and deflection were obtained and recorded from the machine. Further, the maximum bending moment (M) and Stress σ were computed by the author. The tables below indicate the flexural testing results. Table 4.2.2.1 tested five samples of Gypsum Table 4.2.2.2 tested five samples of Gypsum Table 4.2.2.3 Tested five samples of Gypsum with 10% sand Table 4.2.2.4 Tested five samples of Gypflax with 10% sand 4.2.3 Analysis and discussion Figure 4.2.3.1 Load Vs Deflection graph from flexural testing for four samples The most desirable test process for brittle materials is the use of flexural bending stress testing, which is better compared to the tensile stress testing and this helps in preventing crack propagation which may lead to failure when there is tensile load. From the obtained results it is evident that, only the samples from Gypsum gave desirable flexural properties, which is indicated in the graph in Figure 4.2.3.1. Samples of Gypsum are slightly greater than that of Gypflax samples, but the two have a slight similarity in deflection. However, it was noted that despite the presence of better flexural properties, the average stress for the materials were almost the same. Figure 4.2.3.2 Stress Vs samples for flexural testing The Gypsum samples have an average stress of 0.941 MPa, and an average standard deviation of 0.94±0.12, on the other hand samples for the Gypflax has a mean stress of 0.856 MPa and an average standard deviation of 0.9±0.071, thus from the results it is evident that there is very minimal increase in the material toughness. In addition, we reduced 10% from the total Gypsum and replaced the same amount by adding 10% of sand. The same principle was used for Gypflax by reducing 10% of Gypflax and replacing with 10% of sand. Comparing the results for the two samples, Gypflax reinforced with 10% sand, was stronger that Gypsum reinforced with 10% sand. The average stress for Gypflax + 10% sand is 0.6 MPa and an average standard deviation 0.6±0.06, while for the sample of Gypsum that was mixed sand had a mean stress of 0.536 MPa and an average standard deviation of 0.5±0.06 which is lower than that of the other samples as indicated in Figure 4.2.3.2. It was noticed from the experiment that, flax dust can be employed as a reinforcing agent for Gypsum, additionally, adding sand in the mixture helps result help in cost reduction as well as acquiring reasonable flexural test results. 4.3 Charpy testing 4.3.1 Introduction The Charpy test, also known as Charpy V-notch test, can be defined as a typical high strain-rate experimentation, which delimits the quantity of energy used up by a when the material is breaking. Additionally, Charpy test is an experimental test employed to determine material resistance when exposed to blows and other external forces. Material strength declines as the temperature declines, therefore, it is important to consider test temperature (Kutz, 2002, 548). The amount of energy absorbed is the key determinant for the material’s stiffness and acts as a setup to analyse the material temperature-related transition from ductile to brittle. It is often used in industries due to its ability to conduct efficiently and be prepared to other forms. Thus the results can be quickly and easily obtained. Breaking using a single blow from a hammer that is swinging and under standard conditions that have been defined using a notched test piece in the middle, which is supported at the ends is Charpy test. The energy used in the analysis is found in joules. This energy, which is used up is the determinant of the material impact strength. A trial bar that is notched in the centre is supported at the ends of the bar. When the hammer is used to fracture, the bar the energy used up by the bar is a result of the resistance from the material when there is a shock load (Callister and Rethwisch, 2008). The available TUPs were of 7 different types that were used in this experiment and every TUP had its own table indicating conversion energy. To determine the type of TUP to use, it was essential to consider the potential strength and do a practice test for every sample. To get precise outcomes, it is crucial to setup the Charpy rig correctly. Gypsum, GypFlax, Gypflax with sand and Gypsum with sand samples were tested using the correct TUPS to attain the right dial range standards. The dial range measures ought to be between 0.35 and 0.7 if there is any other value obtained outside this range are invalid. Table 4.3.1 TUPS Specifications 4.3.2 Charpy Test Procedure Increase the TUP until to the level of the trigger then tighten it at that point; Move the red indicator on the test dial to the lowest limit; Place the sample on the Charpy test rig anvil; To create an impact by the TUP on the sample, release the trigger; Reading the red indicator of the dial range record the correct value; and By the use of the conversion table, converted the obtained values from the red index into Newtons. 4.3.3 Experimental results Table 4.3.3.1 is the tested five samples of Gypsum. The weight, dial, and impact energy. In this procedure TUP, D was used. Table 4.3.3.2 is the tested five samples of Gypflax. The weight, dial, and impact energy. In this procedure TUP, D was used. Table 4.3.3.3 is the tested five samples of Gypsum with 10% sand. The weight, dial, and impact energy. In this procedure TUP, D was used.  Table 4.3.3.4 is the tested five samples of Gypflax with 10% sand. The weight, dial, and impact energy. In this procedure, TUP E was used.  Comparing the samples used, Gypflax with 10% sand indicated results that it had impact energy higher. Relatively, the other samples had a comparable higher toughness. 4.3.4 Analysis and discussion Figure 4.3.4.1 Average Impact energy Vs samples from Charpy testing Gypflax with 10% sand samples had an average impact energy of 0.85J with an average standard deviation 0.9±0.4, on the other hand, Gypflax had an impact energy of 0.3J and an average standard deviation of 0.3±0.08. It is detected from the experimental results that the impact energy for Gypflax with sand was higher, and this makes is more appropriate for resistance to blast. In addition, when Gypsum with sand and the flux dust are used, it creates more impact energy on thus reducing the Gypsum cost by 10%. With these properties, it can be used to construct structures in areas with high-frequency seismic activities. Moreover, flux dust is obtained waste material its further reduces the cost while it is environmentally friendly, and it has an attractive appearance when used in reinforcement. 4.4 Freeze-Thaw 4.4.1 Introduction The materials ability to withstand wetting that is repeated and accompanied by freezing conditions, which is accounted for by absorption water and behaviour change in compression is referred to as freeze-thaw resistance. Freeze-thaw resistance is regarded as the variation in the quantity of water, that is absorbed and the variation in compression stress or strain a given test sample that is under 300 consecutive cycles from dry conditions at to wet conditions at . For this test, five consecutive cycles were done because the samples available for usage were less (Askeland, and Wendelin, 2013, 207). In this test, samples were placed in a cold chamber at a temperature of (-14 ± 2) °C 1 hour to wet conditions at . The testing procedure is done together with one of the following water absorption tests, which are long term: a) According to EN 12088, water absorption by diffusion; and b) According to EN 12087, water absorption by total immersion. The selected long-term test for water absorption a) and/or b) are rendered in the applicable product standard relating to the practical application. Freezing occurs in the air while thawing takes place in the water (Kobayashi, 2004, 49). 4.4.2 Methodology Equipment used A Cold Freezer that operates at a constant temperature of (-14 ± 2) °C Tank for storing water, which water at a constant temperature of (20 ± 2) °C having a specimen positioning device. Masonry units Methods of test: Before inserting the samples into water, weigh individual samples; Insert the samples in water that is at 20 °C ± 5 °C six times; After the samples have stayed in the water for 5 minutes remove the samples from water; Measured the sample weights when they are wet and then start the freezing cycle after placing the samples in the test positions; The samples were inserted in water at room temperature for 5 minutes and then was done 5 times, which means they were added 5 times to 1 hours, every moment the dry and wet samples were used they were measured to determine their weight; Regulated air temperature in the freezing cabinet to gradually drop to -12 °C from 3 hours to 5 hours and maintained this temperature for at least 2 hours; When the frozen cycle was completed, weight for all the samples was measured; Expose the samples to a series of freeze-thaw cycles while noting the presence of any damages that are visible on the samples based on the following categories: a) Flatness loss, for examples, sample surface bulging; b) Cavities that exceed a diameter of 5 mm; and c) Sample cracking such as surface cracking. If the samples do not indicate damages as per any of the above categories mentioned, then the testing can be done. In the case there are damages on the samples as per the above categories, then determine the sample comprehensive strength when exposed to freeze-thaw cycles and for those that have been separated as per the EN 772-1. 4.4.3 Experimental results 4.4.3.1 Flexural test results The above table indicates the varying times (five times) that the samples were immersed in water recording the weight increase, for example, sample 1 shows an increase in the sample from 14g to 16.5g, etc.  After inserting all the samples in water five times and then placing them in the freezer for an hour and the weight for the frozen samples recorded, for example, sample 2 indicated that the frozen weight increased to 15.8g. The weight increase is attributed to the fact that, the amount of water absorbed when the sample was inserted in the water had frozen, thus making it heavier than that of the dry weight. Then all the samples were inserted in different beakers that contained 400ml of water, and the volume increased to 450ml after inserting the five samples in the beaker containing this amount of water. The change in volume was 50 ml for water in the beaker, which is the volume of the Gypsum sample. The table above indicates weight increase in the samples when the samples were inserted in the water in Five Times. Considering sample 2, it shows an increase in weight from 12.8 g to 15.7g and others are indicated in the table. The samples were put in a beaker five consecutive times then they were put in the freezer for an hour then the weight of the frozen sample was recorded. Observing clearly on sample 1, it indicated a frozen weight of 15.44g. Due to freezing of the absorbed water in the samples the samples became heavier compared to the sample of the dry weight. Then all the samples were put in a beaker that contained 400ml of water and the volume increased to 440ml after inserting the five samples in the beaker containing this amount of water. The change in volume was 40ml for water in the beaker, which is the volume of the Gypflax samples. Flexural test results for mechanical testing after freeze-thaw 4.4.3.2 Freeze-thaw Charpy Test samples results The table above indicates weight increase for the samples when they were immersed in water at varying times (five times). For instance, sample 1 shows weight increase from 8.2 g to 9.8 g and the successive tests are shown a table. Having put all the samples in water five times for 5 minutes and then inserted in the freezer for an hour, they were then removed and the weights recorded, like in sample 4 it indicated a weight of 9.34g after freezing. This increase in weight was attributed to the fact that after the sample was placed into water, water was absorbed and when in the freezer, it was frozen thus increasing the weight of the frozen samples than that of the dry weight sample. Then all the five samples were put in a beaker that contained 400ml of water, and the volume increased to 430ml after inserting the five samples in the beaker containing this amount of water. The change in volume was 30ml for water in the glass, which is the volume of the Gypsum sample. The table above indicates weight increase for the samples when they were immersed in water at varying times (five times), for example, sample 3 shows an increase in weight for the sample from 7.4 g to 9 g etc. All the samples were immersed five times in water and then put in a freezer, which took 1 hour and the weight for the frozen sample was recorded, where for example 2, the frozen weight has been registered as 7.5 g. Since the sample absorbs water, when they were placed in the freezer became heavier than the dry weight. Then all the five samples were put into the beaker that contained 400ml of water and this changed volume of water to 425ml, which means that the amount of the replaced water is 25ml. Charpy test results for mechanical testing after freeze-thaw Table below indicatess the five tested samples of Gypsum. The weight, dial, and impact energy. In this procedure, the TUP F was used. The table below indicates the five samples tested for Gypflax. The weight, dial, and impact energy. In this procedure, the TUP E was used. 4.4.4 Analysis and discussion Some samples indicated physical damages after a number of experimental procedures had been conducted, including: Cracking on the surface to be precise; and Sample surface is bulging. - Flexural test samples Figure 4.4.4.3 wet weight vs. number of the cycle graph for Gypsum and Gypflax The Graph in Figure 4.4.4.3 above indicates the quantity of water that was absorbed by the sample material within the five periods, they were inserted in the water for the duration of 10 minutes for five cycles. The weight increase started from the dry cycle, which was period one then the samples were immersed in a beaker of 400ml of water. For every cycle, there was a slight increase in samples weight until all the five cycles were completed. However, it was evident in the first cycle the weight increased then decreased, which is attributed to the fact that the sample material had been circulated with water and then it started losing the water (Kutz, 2002, 544). It is observed from the graph that, the Gypsum samples absorbs more water than the gypflax samples, and thus the ratio of the water increased in preparation of the Gypflax samples was right, and it is less compared to gypsum samples . Figure 4.4.4.4 Wet samples Vs Freeze samples graph for Gypsum and Gypflax The above Graph indicates a compression between frozen and wet weight for samples of flexural tests. From the results obtained, it is evident that wet samples are heavier than the frozen weights, this is because when the samples are frozen they become lighter than wet samples, which is attributed to the fact that ice is less dense than water (Askeland, and Wendelin, 2013, 208). Additionally, it was clear that the Gypflax samples were lighter than the gypsum samples. Mechanical testing after freeze-thaw (Flexural test) Figure 4.4.4.5 Load Vs Deflection graph from flexural testing for Gypsum and Gypflax samples From the test results obtained, it was clear that Gypflax samples of freeze thaw had better flexural properties. This is evident from the graph in Figure 4.4.4.5. Comparing the Gypsum freeze-thaw samples and the Gypflax samples, the Gypflax sample can stand higher showing slight similarity in deflection. However, the average stress for the samples were almost the same despite the sample having better flexural properties. Figure 4.4.4.6 Stress Vs Freeze thaw samples from flexural testing For the gypsum samples, the average stress is 0.4 MPa, while the average standard deviation of 0.4±0.05, on the other hand for Gypflax the average stress was 0.6 MPa, for the average standard deviation of 0.6±0.03, thus, freeze-thaw samples for Gypsum is less tough than the samples of Freeze-thaw Gypflax. Charpy Test samples Figure 4.4.4.7 wet weight vs. number of the cycle graph for Gypsum and Gypflax Looking the at the grah above, is clear that a much water was absorbed in the five cycles that the samples were dipped in water for the five times in cycles of 10 minutes each. Dry cycle was recorded for cycle 1 then an increasing weight was recorded after the samples were inserted in 400ml of water a beaker, where in every cycle the sample weight increased slightly until the fifth cycle was reached. Comparing the amount of water absorbed by the Gypflax and the Gypsum samples, there is less water absorbed by the Gypflax than the Gypsum sample, which means Gypflax preparation used less water than the gypsum sample preparation. Figure 4.4.4.8 Wet samples Vs Freeze samples graph for Gypsum and Gypflax From the graph above, we compare the freeze and wet weight for the samples used in the Charpy test. Morever, it is observable from the graph, that the wet samples are heavier than the frozen samples because, the frozen sample has less density compared to the wet sample. In addition, the Gypsum samples are heavier than the freeze Gypflax samples. Mechanical testing after freeze-thaw (Charpy test) Figure 4.4.4.9 Impact energy for freeze-thaw Gypsum and Gypflax samples The impact energy that is absorbed by the freeze-thaw Gypflax was 0.75 J and had an average standard deviation of 0.75±0.4. For the Gypsum sample, the amount of impact energy absorbed was 0.4 J and an average and standard deviation of 0.4±0.2. It is evident from the freeze-thaw experiment that, Gypflax had an impact energy that was higher. References Askeland, D., and Wendelin, W., (2013) Essentials of Materials Science and Engineering. New York: Cengage Learning. 207 Kobayashi, T., (2004) Toughness and Strength Materials. New York: Springer Science & Business Media. 41 Kutz, M., (2002) Handbook of Materials Selection. New York: John Wiley & Sons. 548 Read More

It was noticed from the experiment that, flax dust can be employed as a reinforcing agent for Gypsum, additionally, adding sand in the mixture helps result help in cost reduction as well as acquiring reasonable flexural test results. 4.3 Charpy testing 4.3.1 Introduction The Charpy test, also known as Charpy V-notch test, can be defined as a typical high strain-rate experimentation, which delimits the quantity of energy used up by a when the material is breaking. Additionally, Charpy test is an experimental test employed to determine material resistance when exposed to blows and other external forces.

Material strength declines as the temperature declines, therefore, it is important to consider test temperature (Kutz, 2002, 548). The amount of energy absorbed is the key determinant for the material’s stiffness and acts as a setup to analyse the material temperature-related transition from ductile to brittle. It is often used in industries due to its ability to conduct efficiently and be prepared to other forms. Thus the results can be quickly and easily obtained. Breaking using a single blow from a hammer that is swinging and under standard conditions that have been defined using a notched test piece in the middle, which is supported at the ends is Charpy test.

The energy used in the analysis is found in joules. This energy, which is used up is the determinant of the material impact strength. A trial bar that is notched in the centre is supported at the ends of the bar. When the hammer is used to fracture, the bar the energy used up by the bar is a result of the resistance from the material when there is a shock load (Callister and Rethwisch, 2008). The available TUPs were of 7 different types that were used in this experiment and every TUP had its own table indicating conversion energy.

To determine the type of TUP to use, it was essential to consider the potential strength and do a practice test for every sample. To get precise outcomes, it is crucial to setup the Charpy rig correctly. Gypsum, GypFlax, Gypflax with sand and Gypsum with sand samples were tested using the correct TUPS to attain the right dial range standards. The dial range measures ought to be between 0.35 and 0.7 if there is any other value obtained outside this range are invalid. Table 4.3.1 TUPS Specifications 4.3.2 Charpy Test Procedure Increase the TUP until to the level of the trigger then tighten it at that point; Move the red indicator on the test dial to the lowest limit; Place the sample on the Charpy test rig anvil; To create an impact by the TUP on the sample, release the trigger; Reading the red indicator of the dial range record the correct value; and By the use of the conversion table, converted the obtained values from the red index into Newtons. 4.3.

3 Experimental results Table 4.3.3.1 is the tested five samples of Gypsum. The weight, dial, and impact energy. In this procedure TUP, D was used. Table 4.3.3.2 is the tested five samples of Gypflax. The weight, dial, and impact energy. In this procedure TUP, D was used. Table 4.3.3.3 is the tested five samples of Gypsum with 10% sand. The weight, dial, and impact energy. In this procedure TUP, D was used.  Table 4.3.3.4 is the tested five samples of Gypflax with 10% sand. The weight, dial, and impact energy.

In this procedure, TUP E was used.  Comparing the samples used, Gypflax with 10% sand indicated results that it had impact energy higher. Relatively, the other samples had a comparable higher toughness. 4.3.4 Analysis and discussion Figure 4.3.4.1 Average Impact energy Vs samples from Charpy testing Gypflax with 10% sand samples had an average impact energy of 0.85J with an average standard deviation 0.9±0.4, on the other hand, Gypflax had an impact energy of 0.3J and an average standard deviation of 0.3±0.08.

It is detected from the experimental results that the impact energy for Gypflax with sand was higher, and this makes is more appropriate for resistance to blast. In addition, when Gypsum with sand and the flux dust are used, it creates more impact energy on thus reducing the Gypsum cost by 10%.

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