Impact and flexure tests on hampfibre - Essay Example

? Impact and Flexure Tests on Hampfibre An analysis of the given data. Analysis Before analyzing the given data, we must have a look at the basic preliminaries and definitions about the deformation, impact velocity, Hooke’s law and others, Deformation Deformation is the study in continuum mechanics which defines the transformation of an object (material) from its original (reference) shape to a newly adapted form. Deformation can be caused by the external stress (force) effects such as electromagnetic force, gravity, stress, strain and load or temperature. Impact velocity It is the relative measure of the velocity of one object to another in a very small transient time before the interaction of the two objects (interaction could be the result of applied force). In ideal scenario the velocity of the impacting object must not be reduced to 0 and it rarely happens in practical situations. velocity_(impact) = (m_1\vec v_(1f) + m2 vec v_(2f))/m_1 ~ Vec_v shows the velocity vector*. Hooke’s law Hooke’s law is a concept of classical mechanics which discusses the force needed to compress or extend the shape by an amount X (distance). Hooke’s law is also a measure of the deformation of solid bodies as long as deformation impact is small. It is also defined as the first order linear approximation or the material response studied in material science and material engineering (Bansal, 2010). Plastic region: Area under the stress-strain graph after bypassing which, the permanent change and deformation in a material starts occurring. This plastic region is shown in the stress strain graph as the highest point in the curve. Before plastic limit, there is an elastic limit under which the material does not deform itself but it remained confined in the actuality of its originality. However as soon as the elastic and the plastic limit is breached Plastic deformation take place in this deformation, upon uplifting the force and the load, the material does not regain its shape but it tends to adapt the newly deformed shape as the consequence of the load applied to bring about the change of the shape. Stress: Any force applied in purpose to change the shape and objet and to make that object slide against its own structure. \Shear Stress: It is the force which attempts to deform an object by applying pressure on the surface of the object. Sress = Force/Area (i.e. force per unit area) Stress is not a vector. It is a tensor. Elastic Deformation: region in the stress-strain graph where the deformation take place in a transient mode. It means that the deformation in this region is temporary. Beyond this limit, the material experiences plastic deformation which is permanent. Figure #1 The above figure shows the effect of the impact velocity on the three shapes and different samples. The above figure shows that the impact velocity of the 30 degree conical and the 90 degree conical shape is nearly the same because of having a harmony in the shape (as both are conical). The next shape which is a hemispherical shape, the figure shows that it has less impact of the relative impact velocity as compared to the rest of the figures. Because the hemisphere has a changed shape and surface as compared to the conical tip, it exhibits an elasto-plastic dynamic behavior under examination. This also relates with the hemispherical heavenly bodies and other cosmological objects who while colliding with each other do not cause any explosion or sudden disruption, but are slowly deformed resulting catastrophic vibration (seismic) activities. Figure # 2 This diagram shows the effect of the load variation and its results on the various samples of three different shapes. With the varying samples of these conical 30, conical 90 and hemispheres shapes the load is also being shown to be varying and gradually rising under the scenario of the change of the shapes. This shows that as the shapes change the ability to deform an object or bypassing its deforming threshold and the requirement of the force to perform this task varies in accordance with the type of the shape. It also explains that the surfaces like hemisphere requires much force to be deformed than the other shapes. (conical 30 degree and conical 90 degree ). On the hemispherical shape mush of the load is applied to attain the limit of elastic limit or reaching eventually on the plastic region for permanent deformation. Figure # 3 The perusal of the flexure test and the respected time to carry out the process of flexure is being shown in figure 3. It is clearly visible from the figure that the test time varies differently while examining the different samples of the conical and hemispherical conversions. It shows the collective time required to bring about the flexure in the configuration of these objects varies and it is the larger for the hemispherical flexure. From conical 30 to the samples of conical 90 the time required is lesser as compare to the rest of the condition and scenario. Hence the impact on the conical 90 is lesser than the impact exhibited on the other two shapes’ samples. It could also show that the time required for the hemispherical polyester to reach at the plastic region is greater than the rest of the two. Flexure is defined as the change, bend or fold applied to an object or to a tabular organ. The flexure is also referred to as “isostasy” under which an object at first influences outside forces and then adapts the effect of such forces upon itself consequently bending and folding itself under the control of these forces. Figure # 4 This figure elaborates the deformation process in the hempfibre polyester following the basic principles of the continuum mechanics and material science and the construction theory. As we have discussed earlier that Hooke’s law is the measure of the deformation in solid bodies, this figure clearly describes the process of deformation according to the Hooke’s law. It describes that at early stages to carry out deformation greater load is required for the completion of the job in order to breach the elastic limit. Once the elastic limit is reached, the stress-strain graph shows the plastic region which is the peak of the curve. After bypassing this area, permanent changes start occurring within the material henceforth indicating the deformation decaying exponentially and eventually reaching at a zero point. Conclusion. All these graphs and their outcomes discussed above explains the idea and concept of the flexure and impact tests on hempfibre polyester subject to different phases of the deformation under certain conditions. By analyzing different samples under different phases of the load implication and observing the respective deformation, we note that the deformation at first requires greater load until it reaches the plastic limit of flexibility and after bypassing that particular threshold the permanent deformation starts to occur. However in practical scenarios of material science and the mechanics of materials, after passing the plastic region on the stress-strain graph the deformation decays but it never touches the zero point in the x-axis. That is to say that the 0 deformation is impossible to attain because of the decaying nature of the deformation after permanent change of shape. Furthermore the figures also discuss the impact velocity on the hemispherical shape the conical 30 degree and the conical 90 degree shapes under the presence of various samples taken for the test. The analysis of the time of the impact velocity shows that it is lesser for the conical 90 shape as compared to the conical 30 and hemispherical shape and it is the largest for the hemispherical shape among the three shapes. References Bansal, R. K. (2010). A textbook of strength of materials: (in S.I. units). Bangalore: Laxmi Publications. Read More