TIU5814 Building and Construction Technology 2 and Various Engineering

ery strong forces, the key point under observation will be deformation point. The point of the deformation will clearly show how the material is likely to fail when put into proper engineering use. Its original dimensions as the sample under investigation were taken as of the mild steel. The diameter of the sample was taken as D. The area of the cross-section that was used in the experiment was recorded as well.

The main objective of this particular experiment was to establish the behaviour of the steel metal when it is exposed to the variation of forces of different magnitude .The relationship between these forces and the change in the dimensions was given perfect consideration.

The loading type of tensile normally causes the object under study to undergo deformations. The change in the dimensions of the material under test or just the extension process will take place in different forms. Some of the changes are known to be very much slow. This implies that they cannot be detected easily. Some of the changes are very obvious and they give instant results.

=Applied load/area

Such practical forces that results from such pressures are given by deviation of the dimension/original length

It follows that;

…………………………………………………………………………. (1)

 

………………………………………………………………………… (2)

In which

  Refers to the engineering stress

, refers to injected axial force

  Represents known area of cross section

 Represents t change within dimension or the extension,  

Represents the engineering strain.

  Represents the original length.

Young’s modulus

The Young’s Modulus E is given by the formula;

 ………………………………………………………………………….. (3)

A scientist by the name Hooke came up with the law that assists in the prediction of the connection between the applied force and the extension. Such relationship between these two parameters is very important considering that they normally work together. According to this individual, the two quantities are normally related directly that is to say when one value increases the other value too increases. This kind of relationship will continue up to the point when the elastic limit is exceeded. After the elastic limit is exceeded any further increase in the applied force does not produce an extension. This leads to the occurrence of a failure in the components. Most of the metals are known to obey this law apart from the few cases that do not follow the specifics of the same law. Since this law affects nearly all the mechanical behavior of any material, its study is very crucial ((Frazier 2014 (Frazier 2014).

In the practical consideration, the yield point refers to the point in which the law of Hooke does not apply anymore. This simply means that an increase in the stress or the force does not produce any corresponding extension. The most common value of the extension that has been recorded in most of the literature work is just 0.2%. Within this specific value of the percentage, the line that is obtained is normally straight from the origin. Any slight variation in this value amounts to permanent failure or the permanent deformation. The manuals used in the explanation of the properties of various components of the machine will always make reference to this particular point. The exercise of distortion will take place immediately after the value has been exceeded. The reduction in size at the cross section point is called necking. It is of advantage to know the stress value considering that it is affected just before the process of necking starts.

Materials and Equipment’s

• Universal Testing Machine
• Three rods of Mild steel
• A ruler
• Venire Caller

The procedure of the Experiment

The thickness of the rod samples of Mild steels was measured. The width was also taken in dimension. An original dimension of the material sample valued at the length of 80mm. The measurement was taken using a ruler in the confirmation as well as measurement of gauge dimension of the material. The data acquisition software was activated and the selection of the material corresponding or connecting with the material was done within this software. Through starting the cell of the load, the frame of the machine would only be directed to give dimensions of the tensile load in the inserted material. (Toda, Galindo and Rivera 2014).

There was an adjustment of the jaws to fit the specimen’s size. This particular practice was followed by attaching the actual extensometer on the lowered section of the specimen in the gauge. The scroll wheel was used in the preloading of the machine so as to avoid slipping of the specimen

After the removal of the specimen, the extensometers were again adjusted to zero values and the test started for the measurements of the strain of the mild steel rod or sample.

The record of the data was achieved using the software on the spreadsheet. The tensile test was conducted through putting the material in the testing machine at as directed by the technician. Some of the obtained results needed analysis within the computer (Zare 2015). This data was later recovered for further analysis as well as the plotting of the graphs. In order to verify the results, a second procedure was carried out.

During the testing process, the sample was machined using normal operations including turning. The finished product was then introduced onto the machine using the right geometry. A standard machine for testing was used. The results that were obtained from the machine were considered to be very accurate. The substantial measure of the characteristics of the material was achieved through proper positioning of the sample. This is done by holding one of the end samples on a fixed position while on end is displaced at a constant rate. (Wang,  Mattern, Bednar?ík, Li, Zhang and Eckert 2012).

 In order to determine the maximum forces required to cause failure, there was an application of the model. The model established the variation in the extension at relatively slow rate. The equations were used to establish such perfect connections. From the information that was gathered, it was possible to predict the changes in relation to the applied effort. Results and Discussion

Characteristics	Mean	Standard Deviation
Modulus of Elasticity	197.7Gpa	2.0Gpa
Yield  point=7211N	357.1Mpa	3.6Mpa
Ultimate strength=7788N	487.6Mpa	6.7Mpa
Stress Range	From 50  to300Mpa

The force outline dislodging diagram for the 1018 steel inspected is as shown below. The information was changed over to a comparing pressure strain diagram. The diagram obviously demonstrates two areas of direct conduct in low strain position of pressure strain diagram(This, Sistiaga, Wauthle,  Xie, Kruth and Van 2013). This conduct proposes that the example was extremely agreeable at low feelings of anxiety, as well as firm at high feelings of anxiety. Tragically, there is no basic or concoction motivation behind why steel should show an expanding modulus with expanding pressure.

 Consequently, a more plausible clarification was required in realignment and pivot test installation within low pressure (low force) region. Keep in mind that this content installation, as well as the example, is under the equivalent force connected. As these trial conditions concerned, the most agreeable part, therefore, overwhelm the strain conduct pressure.

This data that has been gathered from the experiment that was carried out on the determination of the property of the material was very comprehensive. Proper evaluation of the results indicated that steel will always respond very positively to the forces that it is subjected to. The significant change in the dimensions can be explained by the nature of the distribution of the particles within the structure the metal itself .The large values that are obtained in the variation of the dimensions of the steel sample when subjected to extensional forces speaks volume of the particle distribution within its structure. The magnitude of the forces that was needed to produce extension was almost 605MPa.It is important to note that such magnitude forces apply to those materials with fixed particle distribution. The necking process in the steel metal was the evidence on its characteristics. There was a lot of necking saw in Mild steel.

The changes that have been witnessed in the dimensions of the material that was under the test could not just be wished away. It was the starting point of the evaluation process. The theoretical value of the changes in the dimensions were very much compatible to the actual results that were obtained .The relationship between the force and  the extension within the material translated to a property called pressure strain bends. The compact nature of steel was responsible for the high values in the parameter that were obtained. Creation of space within such structures was found to consume much of the energy. If other materials like aluminum would have been considered for the same experimental tests, the value of the forces in the final results would have been slightly low. The value would have been lower than the indicated possible theoretical digits. This observation therefore implies that the sources of error within the set-up have been greatly minimized. In the diagram, it is very well visible that for designing pressure strain bends, the bends drop downwards subsequent to the necking process (Bassis and Walker 2012).

 However, this phenomenon cannot be found in ordinary genuine pressure strain bends, the bends could achieve the most noteworthy space of break. The computations of the values were done after the results had been obtained from the sample. The machine that was used for the testing operations was only capable of giving comprehensive results after the process of necking took place. The accumulation of the forces slowly led to the variation in the inter particle spaces. As the spaces increased in their volume, the connected computer also recorded the changes. Such versatile modulus was resolved from straight relapse investigation of the test pressure strain information in the second direct area. This region appears alongside the line of anticipated as per the law of Hooke. The values of the forces were 196.76KN for the corresponding extension of 100mm.This value is almost close to the theoretical figures that are found within the literature work of various scholars of material science. Comparison of the gauge with the recorded characteristics of the plain carbon steel was then done after the analysis. The two results were in complete agreement.

The example must be packed with the end goal of zero strain. This showed that this non-zero block came about when the move in strain esteems is realignment and makes the apparatus turn, this is not because of lasting distortion or infringement as in Hooke's Law. The installation realignment area and turn make a few challenges in deciding the point of yield by the 0.2% balance technique. Within the underlying straight region, most of the disfigurement happens in the apparatus furthermore, not in the example. In the meantime, some little measure of inconsistency must happen with an example as the example force might be more prominent than zero. A straight line from the origin is expected when the values are plotted to give graphical interpretation of the entire results. It is important to note that any conclusion that is arrived at in this experiment must be supported by the graph.

Differences between the point of deformation and the maximum axial force.

From the investigation, it may be seen that yield point assesses the power anticipated that would pull a rope, wire, or a helper shaft to the stage where it breaks. Specifically, the unbending nature of a material is the best proportion of versatile weight that it can withhold before the disappointment occurs. Yield quality, or the yield point, is depicted in building science as the reason for worry at which any material starts to deform plastically.

Yield quality is one of the sorts of flexibility. Yield quality is portrayed as the yield weight, or, at the end of the day feeling of nervousness at which an enduring deformation of 0.2% of the primary estimation of the material happens, and is described as the sentiment of tension at which a material can withstand the worry before it is bent for all time (Bardel et al 2014).

Before accomplishing the yield point, the material will damage adaptably and returns to its remarkable shape when there is an imperative and the weight is removed. Past the yield point, there would be a sort of enduring bending in the material which can't be pivoted. In the essential building, the yield is described as the everlasting plastic twisting of an assistant part when push is associated. Unbending nature is based around a considerable measure of components, which joins Elastic Limit – or, as it were, the most lessened worry at which enduring contorting can be evaluated. This needs a mind boggling iterative load-void strategy and is gravely subject to the exactness of the gadget and the limit of the mechanical architect. It is in like manner based around Proportional Limit, the time when the weight strain twist pushes toward getting to be non-coordinate(Wang et al 2012). In most metallic materials, quite far and relating most extreme is by and large vague.

Conclusion

The determination of the properties of the material that suits its applications in the engineering fields was done using the steel rod with specific dimensions. The change or the variation in these dimensions became very important when conclusions were to be arrived at. The specific parameters that were considered useful in the evaluation including the specific point of the yield were noted as well. The results were tabulated as already indicated above. The data that was fed into the computer were directly related to the values that were obtained from the experiment. Reduction in the dimensions of the material under study was the key observation that was visibly made (Aghaie, Honarvar and Zanganeh 2012).

The packing of material must have zero strain in the long run. This should be noticed as non-zero catch came about on the strain move that esteems due to both realignment and apparatus turn, though not due to changeless deformation and Hook’s Law infringement. The installation region realignment and turn make a few troubles in deciding the yield point by the 0.2% balance strategy. In the underlying straight area, most of the twisting happens in the apparatus what's more, not in the example. In the meantime, some little deformation measure happens in the example because the force within example is worthy than zero. This direct region was used in gauging versatile example modulus illustrated; therefore this is to be extrapolated to a stress of zero before deciding the beginning of the example deformation. Thus anticipation of a general line.

References

Aghaie-Khafri, M., Honarvar, F. and Zanganeh, S., 2012. Characterization of grain size and yield strength in AISI 301 stainless steel using ultrasonic attenuation measurements. Journal of Nondestructive Evaluation, 31(3), pp.191-196

Bardel, D., Perez, M., Nelias, D., Deschamps, A., Hutchinson, C.R., Maisonnette, D., Chaise, T., Garnier, J. and Bourlier, F., 2014. Coupled precipitation and yield strength modeling for non-isothermal treatments of a 6061 aluminum alloy. Acta Materialia, 62, pp.129-140.

Bassis, J.N. and Walker, C.C., 2012. Upper and lower limits on the stability of calving glaciers from the yield strength envelope of ice. Proc. R. Soc. A, 468(2140), pp.913-931.

Frazier, W.E., 2014. Metal additive manufacturing: a review. Journal of Materials Engineering and Performance, 23(6), pp.1917-1928.

Thijs, L., Sistiaga, M.L.M., Wauthle, R., Xie, Q., Kruth, J.P. and Van Humbeeck, J., 2013. Strong morphological and crystallographic texture and resulting yield strength anisotropy in selective laser melted tantalum. Acta Materialia, 61(12), pp.4657-4668.

Toda-Caraballo, I., Galindo-Nava, E.I. and Rivera-Díaz-del-Castillo, P.E., 2014. Understanding the factors influencing yield strength on Mg alloys. Acta Materialia, 75, pp.287-296.

Wang, G., Mattern, N., Bednar?ík, J., Li, R., Zhang, B. and Eckert, J., 2012. Correlation between elastic structural behavior and yield strength of metallic glasses. Acta Materialia, 60(6-7), pp.3074-3083.

Zare, Y., 2015. New models for the yield strength of polymer/clay nanocomposites. Composites Part B: Engineering, 73, pp.111-117.