Jute Material - Wet Jute and Dry Jute - Coursework Example

Jute Material Graph 1: Energy-test time graph Impact tests are a measure of resistance to failure that is brought about by application of instantaneous point force. The test compares focuses on the internal strength of the material as it is tested beyond a point where it will break. In these tests comparing dry and wet jute, a few elements are being put to the test. The main concern in the test is the impact of fluid to the internal strength and structure of jute (Vinson and Sierakowski , 2008, p. 210). Dry jute From the graph above dry jute can be taken to be the control subject. The graph that is generated by jute is particularly characteristic of most composite and building material. From the graph, we can learn several facts about the jute that is put under the impact test. Jute occurs as a long, soft and shiny natural vegetable fibre and thus it has to be pre-processed before it is used in any form of construction. The fibre is woven to form laminates, which can be processed into a fibre that can be used in material production. Jute in its natural state is a fibre that is resistant to compressive and tensile stresses and has mechanical properties that are tougher than most fibres (Sadd, 2009, p. 92). The fibre shows it resistance by the time it takes to react to the impact energy impaled on it as shown in the graph it response after 23 milliseconds. The fibre shows resilience to mechanical forces of tension and compression by taking some time before responding to the forces it is exposed to. Once the threshold of resilience is broken at the twenty-third millisecond, the jute fibre begins its deformation process. From the graph, the fibre exhibits elastic tendencies by the steady linear-like deformation through which the material experiences stresses and strains, and handles these deformation forces as if it was a solid beam. The relationship between the test time and impact energy is proportional as an increase in the time shows an increase in the energy amounts absorbed by the fibre. With an increase in the energy of impact, the fibre gets to a place where it cannot withstand any more strains and it begins loosing its elasticity properties. After 28 milliseconds, in accordance with Boresi, Chong and Lee (2010, p. 21), the fibre loses its elasticity element and enters the permanently deformed state. The fibre lingers shortly in the deformation phase, before suffering a complete breakdown in structure in this state. The breakpoint in the dry jute case is recorded at approximately 20.5 Joules. Wet Jute In construction, Jute is mostly used in its dry form. The presence of fluid in the internal structure of jute affects its mechanical properties as displayed in the graph. The effect of having the fluid in the jute is blown up when the material is put under high deformation forces. The wet jute displays similar properties in the initial test phases as depicted by the graph. The wet jute in this case is raw jute, which has not been pre-processed. It is harvested straight from the farms and used in this experiment. In the first stage of testing, the fibre shows resilience to the impact test forces just as the dry jute. It begins to show signs of deformation slightly before the twenty-third milliseconds mark. After which it takes on elastic properties as the dry jute, with the graph being more linear-like when compared to the dry jute. The curve leading to permanent deformation in this case tends to arc more and its start point occurs earlier than that of dry jute. The breakpoint of wet jute is recorded at about 17 Joules. However, it takes about 40 milliseconds for the wet jute to get to the breaking point in the graph. Graph 2: Standard force Test time graph By applying standard force on the subjects, it is easy to establish the ultimate and yield stresses on the fibres. The dry and wet jute display different results in the experiment as indicated by Barsom and Rolfe (1999, p. 291). In conducting this experiment, the dry and wet jute subjects are to be compared. Dry Jute Due to its resistive nature, the dry jute shows signs of being loaded after 23 milliseconds in the test. As indicated by the graph above the progress that follows soon after is represented by a shoot that is almost linear to the almost 2200 Newton’s mark after which the graph begins a drop, which creates a spike. The drop records a low of slightly above 1500 newton after which more force is applied to the jute where it spikes up to a force of 3300 newton. After which the drop follows. The drop is characterised by spikes resulting from the applied force as depicted in the graph in the twentieth and forty-sixth millisecond gap. The uncharacteristic drops in the loading process indicate a difference in dry jute that is uncharacteristic of the normal loading curve on solid materials, and it reveals some characteristics of the dry jute. The test time that is recorded by the dry jute on the load increase is approximately 36 milliseconds after which the load is at the peak. The overall test records a time of approximately 46 milliseconds. From this, it is evident that the unloading or negative slope part of the graph takes less time compared to that of the loading part. The dry jute graph exhibits some unexpected results. Being a solid material, the graph that was expected on loading should have been characteristically smooth (Rees, 2000, p.123), but in this case, it had recorded instances and occurrence of sharp peaks in both the loading and unloading process. Wet Jute Similar to Dry jute the initial test phase resulted in extremely similar results. The loading in the test began showing indications of stress on the material after 23 milliseconds in the experiment. During this phase, the graph of wet jute is particularly uneventful. After the twenty third-millisecond mark, the wet jute graph shoots up linearly as with that of dry jute. In the case of wet jute, the rise hits a high of about 2200 newton. This phase is normally considered as the elastic phase in which upon unloading the stress the material can resume to the original form. The end of the rise in the graph denotes the material has reached the yield point after which increased loading results to fracturing of the material. In this case, the point of yield is clearly defined. With the sharp rise in the graph having reached a maximum, the graph then enters the unloading phase in which the graph results to a rather smooth curve, but one that records an insignificantly small spike in the twenty seventh millisecond phase. After the small blemish on the graph, it continues its smooth curve until it reaches its culmination pint, which is recorded at approximately the hundredth millisecond mark. The wet jute graph exhibits resilient characteristics in terms of durability with the test having provided data up to the hundredth millisecond mark. The loading or impacting phase takes a shorter duration and has a characteristic sharp rise in the graph, which is a result of a loading increment. This follows the trend of the common solid and structural material. There are differences that are evident in the graphs that result from testing both the dry and wet jute which show a difference in their mechanical properties (Park, 2008, p. 211). Conclusion and Discussion The tests conducted on the dry and jute specimen in both cases show stages through which any physical item goes through when put under impact stresses. The graphs, the fibres go through the elastic and permanent deformation phases with a yield point being between the two phases as discussed by Anderson (2004, p. 328). The first test using energy as a measure by which strength of the specimen is tested introduces the Williams principle in linear elastic fracture mechanics. From the data collected, and by following the Williams principle, we can establish the degree of toughness of jute by using the formula U = GICBDΦ (Voland, 2003, p. 182), where is the intrinsic parameter of jute form the total energy used on impact, B is the thickness, D the width and Φ the geometrical calibration factor. It is important to indicate that the graph shows two major differences in dry and wet jute. Dry jute records higher strength, whereas wet jute has a higher elasticity index (Gere and Goodno, 2008, p. 129). The second pair of graphs where standard force is applied to the dry and wet jute shows one major difference between the two specimens. In the case of dry jute, the graph has spikes, which are not the norm when considering solid and basic construction material. The spikes represent a structural difference where dry jute is brittle when compared to wet jute that seems to have a ductile structure (Callister and Rethwisch, 2009, p. 291). This further explains the difference in the time taken for a complete deformation, with wet jute taking longer than dry jute. References Anderson, T.L. (2004) Fracture Mechanics: Fundamentals and Applications, 3rd edition, London: CRC Press. Barsom , J. and Rolfe , S. (1999) Fracture and Fatigue Control in Structures, 3rd edition, London: Butterworth-Heinemann. Boresi, A.P., Chong, K. and Lee, J.D. (2010) Elasticity in Engineering Mechanics, 3rd edition, New York: Wiley. Callister, D. and Rethwisch, G. (2009) Materials Science and Engineering: An Introduction, 8th edition, New York: Wiley. Gere, M. and Goodno, B. J. (2008) Mechanics of Materials, SI Edition, 7th edition, Boston: CL Engineering. Park, S. (2008) Fundamentals of Engineering Economics, 2nd edition, London: Prentice Hall. Rees, D.W.A. (ed.) (2000) Mechanics of Solids and Structures, 1st edition, New York: World Scientific Publishing Company. Sadd, M.H. (2009) Elasticity: Theory, Applications, and Numerics, 2nd edition, New York: Academic Press. Vinson, J. R. and Sierakowski , R. L. (2008) The Behavior of Structures Composed of Composite Materials (Solid Mechanics and Its Applications), 2nd edition, New York: Springer. Voland, G. (2003) Engineering by Design, 2nd edition, London: Prentice Hall. Read More