Mechanical Strength of Mild Steel

Mechanical Strength of Mild SteelIntroductionCE 2.1 One day on National Geographic channel I was reflexion a program in which they were experimenting with the finite element analysis softwargon system to observe structure and thermal load effects on the wing of Boeing 747s wing. Luckily, during the kindred time, in my 8th semester back in 2013 we were taught the introduction to Finite Element Methods by our professor, Dr. Ijaz Ahmed Chaudhary in University of Engineering and Technology, Lahore. The curiosity in that subject laid the sign foundations of my interesting project named as Drop Test Calculations for Mild Steel where I worked as a Team Leader. This experience paved my way to deuce more leadership roles.BackgroundCE 2.2 It was almost four years in UET Lahore. And organism a student of engineering I almost had the organic knowledge of the field by that situation. I wanted to work my notional knowledge in some practical way. I had already studied the chemical mechanis m of materials 1 and 2. And performed various experiments in lab to find out the material properties such as ductility, malleability, brittleness and toughness. In 8th semester ANSYS was being employ as external load analysis software in Finite Element Analysis course. I was assigned a project to select a report and perform it in the lab and as well as analyze it using ANSYS. That was a good opportunity to gain practical experience and contain the knowledge of Mechanics of Materials and Finite Element Analysis.Nature of ProjectCE 2.3 This project included the calculation for crepuscule testing of mild steel. In effort and real world different items and object face different kind of environmental conditions. Drop testing was used for dump loading effects. First of all, theoretical modeling was done for drop t adapted to check either items lowlife survive shock or not. Then commercial finite element software was used to investigate the response of drop circuit board.Objective of the ProjectCE 2.4 The objective of the report was to determine mechanical strength of mild steel. I had to use drop testing method then I investigated its behavior on finite element software.Nature of My Particular Work AreaCE 2.5 In this project, I had to perform calculations for drop postpone by taking it as a fixed beam at both ends and applying a sinusoidal shock load of 100 gram. Then calculations were made to calculate the maximum binding stress produced in drop remit.CE 2.6 Organizational StructureCE 2.7 averment of DutiesBeing leader of the group my scope of duties includedTo plan the project for timely completion.To make work packs to ensure health and safety.Conduct meeting with members and supervisory program for mutual feedback.Theoretical calculation of drop test mechanism on mild steel.Report writing and technical foul presentation.Personal Engineering ActivityCE 2.8 I started with literature review about drop testing and FEA on internet and library. Subsequent discussions with my professor led me up to kick off my calculations. The mho step of course was to select certain parameters and their dimensions for drop testing. These parameters are given in the put off below.The drop table material and the shock load order was assigned to us by our professor. I chose the dimensions of the table and mass of test item carefully. If the mass of the table is too less it wont be able to bear the shock itself let alone the test item. To make things more clear, test item is always on the top of table when shock is being applied on it.Now the next step was to calculate the weight of the table.Table thickness = d = 0.0125mTable length = l = 0.3mTable width = b = 0.3m weightiness of the table =W1 = density * volume*gW1 = 86.75 NWeight of the test item = W2= 20KG = 196 NTotal Weight = W = W1+W2 = 282.75 NMoment of Inertia = I = 4.88 * 10-8 m-4The rest of the calculations are shown belowTo calculate shock factor, F, I needed to calculate . Shock duratio n, , is 0.01 s and the natural time period, , is given as belowWhere ,, is the static deflection and is calculated as followsWhere,W = Weight per unit length, N/m = E = Youngs modulus of Elasticity of Mild Steel = 210 x 109 N/m2So, after substituting the values in the above equationHence,As a result,CE 2.9 By using the graph below in underframe 1, we deduce that F factor comes out to be 1.2.Figure 1 Calculation of Factor FMoreover, some of the basic calculations are done belowDynamic load is calculated as Pd = F * M * AA= Applied Shock = 100gM= Total Weight/gravitational force (g)Therefore ,Pd = 33930 NewtonNow, I have to calculate maximum flex stressMax Bending Stress =(Bending Moment * Distance from axis)/ InertiaMax Bending Stress = 48.88 MPaI verified the bending moment calculations as they were performed by my team mate and it is beyond the scope of this report to discuss it fully here.CE 2.9 According to the principle of mechanics, if the maximum bending stress produced by the applied load is less than the ultimate tensile strength of the material then the material can withstand the applied load without failure and vice versa. In this case, since the ultimate tensile strength of mild steel is 165 MPa which is greater than the maximum bending stress of 48.88 MPa produced by the applied load, drop table will easily sustain the 100 g shock loading.CE 2.10 Computational dynamics came into play in the form of FEA as I used ANSYS to simulate static deflection of the drop table subjected to 100 g shock loading. The load is applied on the top surface of drop table in form of pressure and both ends of the table are fixed by using fixed support. Material properties used for the drop table are shown in the figure 2 below.Figure 2 Material properties of the test pieceCE 2.11 I still remember that there came a point where my team was in truth much stressed out because of the criticality of the extensive calculations involved. In fact, my team failed in couple of iterative processes and they wanted to give up on this project. I summoned a meeting where I emphasized on the fact that every failure is itself a step towards success. By omitting those factors which are do us disappointment should be identified and removed. My team appreciated the gesture and went on to complete the project with more enthusiasm and that is when we finally got the 3D occupy of the work piece as shown below in figure 3Figure 3 3D meshing of the drop tableThe parameters for meshing dilate are show in figure 4 below.Figure 4 Meshing parameters obtained during FEACE 2.11 After the meshing, the sinusoidal shock load of 100 g, shown in figure below, depicts that the maximum Von Mises stress produced in drop table amounts to be 50.23 MPa. Our theoretical calculated maximum stress comes out to be 48.88 MPa. Again, I can surely say that this stress is within the bearable load limits of the table load and hence wont fracture. The stress patterns are shown in figure 5 belo w.Figure 5 Static structural analysis of drop tableCE 2.12 Mild steel is a very stiff material so a very high shock wave is generated when drop table hits the mild steel. On the other hand, due to its stiffness the duration of the shock is very low. In case of mild steel peak shock value calculated was 55.84 g when a drop table is dropped from a height of 330 m. on a lower floor figure 6 depicts this behavior in the form of a graph.Figure 6 Shock loading VS Time GraphCE 2.13 Von Mises stress contours produced when drop table strikes with mild steel attached sensors are shown in the figure below. Stress contours clearly shows that high stresses are produced in region where drop table makes contact with the object. Highest stress produced is 49.9 MPa as shown in figure 7.Figure7 Von Mises stress contours produced in case of mild steel programmers contactCE 2.14 As we had to use testing ground with heavy machinery and metal pieces, I made sure that every used proper safety procedure s uch as wearing PPE. Toolbox talks and near miss discussions were conducted before every session. That was the reason project was completed without any accidents.SummaryCE 2.15 The timely completion of this project boosted up my technical knowledge and had an ever lasting impact on my people and time management skills. Later on, during one of my internships I realized that my quality check incision was facing a material failure issue. Keeping in view this project I performed the drop testing and deduced that the material wasnt strong enough to stand the stresses and buckled in extreme loading conditions. My study was well praised and they switched from Steel to Aluminum and since then have got fewer failures.