AutoCAD Drawing of Final Design Choice - Essay Example

Introduction to Engineering Design ENF1204 0Executive summary Comprehending structural behavior of any bridge is a significant aspect of engineering. This is because it aids in comprehension of the concepts of load transfer via the structure by tension and compression and corresponding equilibrium of underlying forces within a static analysis of the structure. The report aims at analyzing the construction and testing of the prevailing under sluing truss bridge with close attempt of coming up with suitable conclusions concerning the behavior and the corresponding challenges normally encountered by the real world of engineers. The bridge was built to a scale of 1 to 40 with total clearance span of 500mm, utilizing craft sticks and PVA glue. After building of the bridge, it was tested to eliminate fatigue failure via application of the mid span within a laboratory setting. Moreover, the collapse is the position at which the underlying structure cannot support further escalation of load or a deflection beyond 30mm. The prevailing truss bridge passes the failure test. Moreover, the greatest load of 3.5kN was the second load applied to any bridge test, which excessively exceeds the needed load of 98N by the corresponding factor of 36. The prevailing weight ratio of 11.7 was compared satisfactorily with the existing supplementary bridges tested to enable successful design. Nevertheless, the graph of the load against deflection was not ideal thus depicting defects within the construction as depicted by the failure of the bridge. Advanced bridge possess relatively greater links amidst the prevailing craft sticks by utilizing sturdier clamps thus will improved the bridge by offering greater quality links amidst the underlying middle trusses and the corresponding bottom beams to avert it from slipping out. 2.0 Table of Content Table of Contents 1.0Executive summary 2 2.0 Table of Content 3 Table of Contents 3 3.0 Introduction 4 4.0 Aim 5 5.0 Bridge Design 5 5.1Design options 5 5.2 Data analysis 6 5.3 Design Choice 9 6. Construction 9 Equipment and Materials 9 6.2 Method 9 7. Test Results 11 8. Discussion 11 9. Conclusion 13 Appendices 14 9.1. AutoCAD Drawing of Final Design Choice 14 References 15 3.0 Introduction Bridges are observable accomplishments of engineering presently. Originally, the bridges composed of relatively simpler structures purely made from easily reachable natural resources. The natural resources entail timber, stone and dirt, which were operational though they had shorter life span thus resulting to weak structural bridges. Conversely, modern designs for trusses possess greater spaces to be spanned. A truss design is normally favorable to numerous engineers in modern world, since they are affordable and have high structural integrity. Comprehending structural behavior of any bridge is a significant aspect of engineering. This is because it aids in comprehension of the concepts of load transfer via the structure by tension and compression and corresponding equilibrium of underlying forces within a static analysis of the structure (Onwubiko, 2000). The report aims at analyzing the construction and testing of the prevailing under sluing truss bridge with close attempt of coming up with suitable conclusions concerning the behavior and the corresponding challenges normally encountered by the real world of engineers. The bridge will be built to a scale of 1 to 40, clearing a total span of 50mm. The underlying limitations within the design conditions area maximum of 25mm either side of the span, maximum width of 110mm, a maximum under slug of 110mm and maximum height over the underlying abutments where the bridge is 20mm. The bridge will be built utilizing crafts sticks and corresponding PVA glue (Hunt, 2013a). After construction of the bridge, it will be subjected to failure test at the mid span within the laboratory setting. Collapse is normally the location at which the prevailing structure cannot support any further escalation of load or a deflection exceeding 30mm. 4.0 Aim The main aim of the project is to design and build an under slung truss bridge that is capable of withstanding 10kg mass applicable at the mid span to the structure in line with the structural safety needs of an Ausraods design. The strength to weight ratio will be employed in the bridge. The project targets to build the brightest structure that can endure a maximum load with least deflection. 5.0 Bridge Design 5.1Design options Numerous designs were developed for the corresponding analysis according to the good engineering practice. The original design used trusses on a 45⁰ angle (Onwubiko, 2000). This angle is the best distributed load over the underlying structure. Nevertheless, due to the existing limitations, the design demands seven triangular sections that potentially decreased the integrity of structure. Design option 2 The design entails radial arrangement of centrally applied loading range evenly across the prevailing structure. The benefit of the design evenly does not allocate the load thus not demanding large number of the craft sticks to fabrication. Nevertheless, it is normally cumbersome to build precisely. Design option 3 The design entails simple three triangular truss bridge utilizing maximum depth design constraints. Moreover, it was designed as the main compromise to maximize the underlying angle of the truss towards the existing ideal of 45⁰ whilst diminishing the number of triangular segments. Nevertheless, the flaws within this design were favorable at 45⁰ angle for the corresponding trusses. 5.2 Data analysis Utilizing an existing online program the forces in every beam were subjected to a static analysis having a constant load. This is normally permitted for every bridge assessment and corresponding greater design to be chosen for building. Moreover, the analysis is permitted for suitable determination of thickness of every beam to advance efficiency. The steady load applicable to the design force is 1000N, which reliable with the underlying minimum specifications of the outlined activity. The design option 1 possessed steady force within the angled trusses. Nevertheless, there is relatively larger force on the top and bottom beams mainly nearer to the centre. The maximum force of 2000N is at the centre of the prevailing bottom beam implying that the failure would be at the centre. To avoid failure, much craft sticks would be utilized in reinforcing the positions. Nevertheless, it would result to additional weight on the entire model bridge. Figure 5.2.1 – Static Analysis of Design Option 1 The design option 2 depicts the radial design with the capability of distributing the load evenly on the existing trusses. The maximum force of the truss on the design 135N less than 200N of design option 1 as displayed on the figure5.2.1. Thus, the design is relatively smaller chance of the failure within the lower beams. The middle compression beam with a force of 40N does not carry massive load thereby aiding in the determination of the number of craft stick utilized on the beam. Figure 5.2.2 – Static Analysis of Design Option 2 Analysis of design option 3 depicts that the design possesses the least maximum force of 135N on the beam. This implies underlying design is capable of distributing the load efficiently devoid of exerting much force on a sole beam. The beams at placed at an angle with identical force of 83N thus enabling easier decision of the number of the craft sticks to be utilized within the positions. Moreover, the analysis depicts that the existing top truss beams does not require much craft sticks for reinforcement as compared to the corresponding truss hence reducing the entire weight of the design. Figure 5.2.3 – Static Analysis of Design Option 3 5.3 Design Choice The model truss beam choices is mainly based on utilization of the beams that are placed at 45 degree thus improving the effectiveness by distributing the loads to other corresponding beams. Design option 3 having three triangular sections is the best based on the online Bridge Designer since it has the least amount of force on a sole beam and least design constraints. It also spread the load equally making it relatively simpler to build utilizing the available equipment. 6. Construction Equipment and Materials 1. Craft sticks 2. PVA glue 3. Hack saw 4. Clamps 5. Pegs 6. Pliers 6.2 Method Designing of the bridge for construction entail set schedule for the project, which ensures that the glue have sufficient duration to dry. The design has massive strength and weaknesses of the materials. Moreover, craft sticks are normally strong in tension and compression whilst their corresponding flaw is within their flex. Construction alternatives are mainly based on the underlying design via the modular method. Modula method stipulates that every element ought to be built individually prior to being linked to the end. Side view AutoCAD drawing was then drafted with suitable dimensions in order to make the construction process easier. Moreover, hand drawing was drawn for every element to make sure that the joins easily slot together. It also ensures there is no misunderstanding amidst team members and concurrence of each element mainly based on the prevailing analysis within section 5.2 of the report. After drafting fundamental layout of the frame, individual elements are built, which is undertaken by cutting specific craft sticks to the suitable length with the existing hack saw, layering craft sticks with PVA glue, and corresponding clamping the pieces utilizing pegs (Onwubiko, 2000). This was significant in construction of every element with the bridge required thus enabling adequate it to endure fundamental forces. Peculiar attention is laid on the top bar where there is application of load and reaction forces. This section of the bridge is utilized for craft sticks thus offering possible rigidity to the structure. The two sides of the prevailing truss were made independently with much emphasis on the larger stress (Hunt, 2013a). This is depicts the action of reaction and the bottom truss parts within tension thus adding extra reinforcements thereby adding the surface area in contact and consolidation of the bridge. After drying glues every side of the bridge are links with cross members, which is normally undertaken on the small members of the craft sticks across the top and bottom for inflexibility. Additional cross members are then added beneath every end of the bridge where there is action of the reaction forces thus offering additional strength to a basic part of the bridge. Moreover, the structure is left to dry up for numerous days then tested. 7. Test Results Figure 7.0.1 - Load as a function of Deflection 8. Discussion The truss bridge carried maximum load of 3.5Kn with the corresponding deflection of 13.6mm, which aids in comparison of favorable demanded in loading 10kg by corresponding factor of 36. The Figure 7.0.1 depicts load taken by bridge as the main function of the deflection. The shape of the underlying graph is described as horsetail making it to steadily increase and deflecting the load up prior to stressing the bridge to large and fail with no extra load for deflection. Within the figure, 7.0.1 depicts the increase steadily from 0-3kN with slightly displaying classic horsetail as the bridge to partially fail then continues to load until it reaches its highest at 3.5Kn. It then deflects by taking no extra load. The examination of the bridge failed in two places that is bottom beam tore apart under the force of the tension and the other middle trusses lipped out of its underlying force of compression. This is displayed in the appendices 9.2 and 9.3 correspondingly as depicted in the figure 7.0.1. The partial failure at point 3Kn is due to slipping of the middle truss out of the place as the glue fail whilst the ouster truss and cross struts, which permitted the bridge to perpetual increase in load. Escalation of the load above 3.5kN makes it to become larger for the bottom beam and the glue attaching it together to fail as depicted in the appendix 9.3. Moreover, this position the bridge cannot take any more load thus not deflection (Onwubiko, 2000). The result of the graph for the load on the bridge increased swiftly due to small deflection until the load becomes massive making the bridge to snaps. This results to production of a graph having steeper slope within the original increase to the optimal point then swiftly decreasing. The decrease depicts flaws within the construction of the bridge. Suitable construction of bridge at the joints and failure with the existing trusses snaps due to the load thus becoming very massive for the materials. Source of failure in the construction is pegged in the utilization of the clamps. The pressure is created by the pegs is relatively less as compared by the deal thus resulting to weaker members as depicted by the failure of the bottom beam within the compression. Weak position within the design is in the joints amidst the middle compression trusses and the corresponding bottom beam due to lack of adequate contact amidst two elements. An advanced bridge is developed with identical fundamental design utilizing upper quality clamps to ensure a good contact amidst craft sticks coupled with better middle trusses to avoid their slipping out and negotiating the physical integrity. Nevertheless, the main aim of the activity was mainly to attain sufficient strength to corresponding weight ratio. The ratio is computed by dividing the existing maximum load prior to failure by the weight of the underlying bridge. Moreover, the weight of the bridge was 340g whilst the maximum load is standing at 3560N, which is equivalent to the strength to the prevailing weight ratio of 11.7. This equates to the favorable bridge tested, which is best accomplished by the ratio of 10.8 weighing 367g with maximum load of 3.95Kn. 9. Conclusion Truss bridge is the best as it has maximum load of 3.56Kn as the second largest load from bridge tested. The tested bridge exceeded the demanded load estimated at 98N by the corresponding factor of 36. Moreover, the strength to weight ratio of 11.7 compared favorably with other existing bridges tested thus making the designing process success. Nevertheless, as depicted within the discussion, the prevailing load against the existing deflection graph is not ideal, which depicts locations of flaws within the construction process as seen in the bridged failure. Advanced bridge would be relatively higher quality links amidst the craft sticks by utilizing stringer clamps and improving the connections amidst the middle trusses and the corresponding bottom beam to prevent from slipping. Appendices 9.1. AutoCAD Drawing of Final Design Choice 1. Photograph of Middle Truss Tearing Glue Under Compression 2. Photograph of Bottom Beam Glue Tearing Under Tension References History of Bridges 2013, Ancient Roman Bridges, viewed 12 August 2013, Hunt, K (2013a), Structural Activity – Truss Bridge Requirements, lecture notes, Introduction to Engineering Design ENF1204, Victoria University, delivered 31 July 2013. Hunt, K 2013b, Structural Activity – Truss Bridge Requirements, lecture notes, Introduction to Engineering Design ENF1204, Victoria University, delivered 7 August 2013. Ozansoy, C & Iveson S 2013, The Engineering Method, lecture notes, Engineering and the Community ENF1103, Victoria University, delivered 12 April 2013. Virtual Lab 2013, Bridge Designer, John Hopkins University, viewed 5 August 2013, http://www.jhu.edu/virtlab/bridge/bridge.htm Onwubiko, C. O. (2000). Introduction to engineering design optimization. Upper Saddle River, NJ: Prentice-Hall. Bilén, S. G. (2001). Introduction to engineering design. 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