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Engineering industry changed the people's ideas of boundaries, limits and distance. With the arrival of the new software's, people suddenly had the freedom faster and faster than ever before. It changed the way the people live and the way they travelled, making an impact on people live their lives and even how they behave on their daily basic.
Engineering played a major role in making the industry the important field that it is today. Engineering thoughts and new innovations in the field of engineering found throughout the history. An engineering innovation was more than the improvement and development of parts. The production or manufacturing process itself a innovation in engineering field. Engineering industries thus remains the important and offer a challenging carrier with the potential to make a significant impact on society.
This report shows the process of the computer aided design that can be used to help engineers with their work. The used technique is used to accelerate a design process and make a designer effort more efficient.
Design optimisation is widely used in modern industry as it is crucial to engineers to minimum cost and weight to stay competitive. Design optimization is the application of numerical algorithms and techniques to engineering systems to assist the designers in improving the system's performance, weight, reliability, and/or cost.
Design optimization methodologies can be applied during the product development stage to ensure that the finished design will have the high performance, high reliability, low weight, and/or low cost. Alternatively, design optimization method can be applied to existing products to identify potential design improvements.
It is fundamental to understand the design load path at the early stage of design as well as being aware of the production volume, the part cost, structural stiffness and strength requirements.
The objective of the present project work is
To study the use of weight optimization by designing 3D bracket using HYPERMESH and CATIA.
To study the loads (forces) and constraints to get the maximum Induced stress in the 3D bracket.
For the optimization and analysis of a component or part of any machine, first we have to Design the model and make it and assemble it and we can analyze and optimize it by applying the forces.
In this present project, we are optimizing the 3D bracket by using software called HYPERMESH and building a 3D CAD design model using software called CATIA. Again importing the 3D CAD design in hyper mesh to analysis. In which we consider all the condition and find out the induced stress in each case and compared it with the Allowable stress for the structural constraints, cost and manufacturing requirements.
This chapter describes the weight optimisation by designing a 3D bracket within a design space, structural constraints, cost and manufacturing requirements.
2.2 MATERIAL TYPE
The material used for the weight optimisation is steel.
2.3 DESIGN SPECIFICATION
Height = 300mm
Width = 250mm
Length = 300mm
2.4 LOADS AND CONSTRAINTS
Forces = -400N (in x- direction)
= 5000N (in y- direction)
= -1000N (in z- direction)
Displacement = All DOF
2.5 PRODUCTION UNITS
The number of production units for the design optimisation of 3D steel bracket is 10.
2.6 OPTIMISATION PROCEDURE
The procedure of modelling and optimisation is as follows:
Firstly create the cuboid model using the design specification in CATIA software (300x250x300) mm and then import that model in HYPERMESH software for optimization of bracket.
Then create material which is steel and property which is solid property and assign the material.
After assigning the material give the element size for meshing and mesh the model which is tetra mesh and create the boundaries and forces in load collector.
Then assign the constraints in any one direction. And apply the forces in three directions and analysis the model.
Now the optimization should proceed and give volume, displacement in response and provide de-constrains for the model and maximum deflection for each load case should not exceed 5mm.
Give the optimization constrains for x, y and z directions and then give the objective for the volume.
For optimization of steel bracket we have to then opt strut the model. It will give the iteration for design and value of design volume fraction.
Go for Hyper view and give yours design volume fraction value for highest iteration of design model for design history.
On optimization, the maximum and minimum element densities, displacement and element stresses for d1, d2 and d3 are recorded.
The optimization was repeated with different direction of force and element size and the stress values were check with that of the allowable stress of the material.
Figure 1: Model with mesh size and constrains
In this i have taken 8 constrains in x direction with mesh size 12. Then the optimised shown below
Figure2: optimised shape of bracket
The 2nd satisfied convergence ratio = 3.5437E-03
Minimize VOLFR =1.18751E-02%
Change = -0.35
Maximum Constraint Violation % = 0.00000E+00
Design Volume Fraction = 1.18751E-02
Mass = 2.11080E-03
Sub case Compliance
Material selection process:
Material selection is an important part of the design for a component or product. Depending upon the selection of material the whole manufacturing or production process will depends. Because design, material and manufacturing process are interrelated with each other (cyclic process).
A design will have a certain profile of material attributes such as
High yield strength
High young's modulus
Similarly, if we are choosing an unsuitable material or manufacturing process will lead to poor component performance and reliability which in turn can lead to
In service failure
Damage to surrounding infrastructure ( plant and machinery)
Injury to persons
Rectification costs, compensation, litigation.
Material grade chosen:
For the design optimisation of 3D bracket we have chosen the material as steel. They are different types of steel such as carbon steel, alloy steel, stainless steel and tool steel. For each and every type there are different types of properties at room temperature (25°C).
Let us consider the carbon steel which has density (1000kg/m3) of 7.85, elastic modulus (Gpa) of 190-210, poission's ratio as 0.27-0.3, young's modulus (Gpa) as 200-216 and yield strength (Mpa) as 186-758.
Carbon steels have Balances ductility and strength and has good wear resistance, and it is used for large parts, forging and automotive components.
Steels are widely used in construction of roads, railways, infrastructure and modern structure such as stadium and airports which are supported by steel skeleton. In addition to it steel was widespread use in major appliances and car.
3D CAD design:
The optimised bracket which has come in HYPERMESH then convert into OS smooth file and open in CATIA software which will provide a 3D solid modelling for the bracket. Depending upon the design the production route imparts.
Steps involve in CATIA:
First create a plane that is parallel through points.
Select a rectangular block for the optimized bracket which will in 3D solid model. Trim the unwanted material from the design because as it importance to maintain a minimum cost and minimum weight.
Select the plane in which we have to remove the material and sketch the material and go to pocket command and preview the design if it is padding the material required to design requirement then trim the unwanted material.
Similarly, selecting the plane for which we want to remove the material and acquiring the desired bracket design.
Once we get the desired shape then analysis the model by applying the forces.
Figure3: padding of material
Figure 4: padding of material
Figure 5: padding of material
Figure 6: padding of material
After removal of unwanted material from the optimized bracket the desired shape of 3D solid design bracket is
Figure 7: 3D design of bracket
Once we achieve the 3D CAD design then analysis that design to see that can withstand the load and constrains.
For the analysis of design model import again in HYPERMESH
First create material which is steel and property which is solid property and assign the material.
After assigning the material give the element size for meshing which is 10mm and mesh the model which is tetra mesh and create the boundaries and forces in load collector.
Then assign the constraints in fx-direction and apply the forces in three directions and analysis the model.
On solving, element stresses, von Misses stresses and displacement were analyzed and recorded.
Figure 8: 3D model with mesh size
Figure 9: element stresses
Figure 10: Displacement
Volume = 3.19000E+06
Mass = 2.52010E-02
Sub case Compliance
Selection of manufacturing process:
In an industry manufacturing process interrelated with design (function, shape) and material.
Now a days there are different types of manufacturing technologies that had the potential to deliver a product with the desired mechanical and weight properties, minimum post-process finishing and potential of meeting the cost target.
Characteristics of manufacturing process:
Ability to generate certain geometries
Good tolerance attainability
Produce good economic batch size
Ability to control capital cost
There are different types of manufacturing processes such as:
Each process can be characterised by a set of attributes such as:
Economic batch size
But compare to all processes with mass and production units sand casting is one of the best processes to consider for manufacturing and production.
Manufacturing process of steel bracket:
Sand casting process:
A sand casting probably started on beaches it is a cast part produced by forming a mould from a sand mixture and pouring molten metal liquid into the cavity in the mould is then cooled until the metal has solidified and in last pattern is removed to leave the cavity in which the metal is poured.
The increasing demand for castings in the growing car and machine building industry, stimulated new inventions in mechanization and later automation of the sand casting process technology, with the fast development of the car and machine building industry the casting consuming areas called for steady higher productivity. The basic process stages of the mechanical molding and casting process are similar to those described under the manual sand casting process. The technical and mental development however was so rapid and profound that the character of the sand casting process changed radically.
Figure 11: schematic diagram of sand casting
[CES Edupack 2008]
There are basically six steps involve in sand casting process such as:
Place a pattern in sand to create a mould
Incorporate a gating system
Remove the pattern
Fill the mould cavity with molten metal
Allow the metal to cool
Break away the sand mould and remove the casting
The material costs for this process are low and the sand casting process is exceptionally flexible. The production can be made in huge quantity and the mold material is recycled between 90-95%. This process is suitable for making large parts.
Good surface finish
Capital and tooling cost are low
Mould preparation time is relatively short
Can achieve very close tolerance
Process cannot make thin section
Fine silica dust and organic additives may create health hazard
High labour cost and time consuming
The manufacture of a component consumes resources each of which has an associated cost. The final cost is the sum of those of the resources it consumes. Thus the cost of producing a component of mass m entails the cost Cm (£/kg) of the materials and feed-stocks from which it is made. It involves the cost of dedicated tooling, Ct (£), and that of the capital equipment, Cc (£), in which the tooling will be used. It requires time, chargeable at an overhead rate (thus with units of £/hr), in which we include the cost of labor, administration, and general plant costs. It requires energy, which is sometimes charged against a process-step if it is very energy intensive but more usually is treated as part of the overhead and lumped, as we shall do here. Finally there is the cost of information, meaning that of research and development, royalty, or license fees; this, too, we view as a cost per unit time and lump it into the overhead.
Figure 12: Input to a manufacturing process
Relative cost index:
The below graphs shown the manufacturing cost after applying the production batch size and the component mass. Depending upon the values of mass what we get and the production units the graph shown below:
Figure 13: Batch size
Figure 14: material cost
[CES Edupack 2008]
For the cost estimation of 3D solid design with the design optimisation valve of Mass = 2.52010E-02 for production unit of 10. The physical and economic attributes are shown below
Mass range : 0.01 to 1e4kg
Tolerance : 0.8 to 3 mm
Relative tooling cost: low
Relative equipment cost: low
Economic batch size (units): 1 to 1e5
Bracket installation procedure:
While it's certainly possible to simply nail your Brackets into place, you can achieve more professional results by following the easy steps outlined below.
Hold the first Bracket in place, and mark appropriate screw locations onto the front edge of the Bracket. For most installations, two well placed screws are adequate to secure the Bracket.
Pre-drill screw holes large enough to allow the body of the screw to snugly fit through the Bracket, without using a screw driver. The larger screw head will actually hold your Brackets into place.
Mark the position of centre of the Bracket will occupy. It's typical to install Post Face Brackets on the centre of the Post.
Make additional marks to the left and right of your previous centre mark, to indicate the Bracket's thickness.
Extend one of these side marks the full length of the Bracket, to serve as an alignment guide during installation.
Hold the Bracket into place, aligning one edge along the line you extended in the previous step. Use a small carpenter's square to also position your Bracket at a right angle to the surface upon which you are mounting the Bracket.
Screw each Bracket into place, repeating these seven steps until all Brackets have been installed. You may find it helpful to drill pilot holes into the mounting surface. These should be slightly smaller than the body of the screws for a good hold.
The aim of this assignment is to demonstrate the use of weight optimisation by designing a 3D bracket. The first and the foremost thing that why we are optimising the 3D bracket is to reduce the mass and to maintain minimum cost. To reduce cost of manufacturing the final component will be symmetrical.
In this result, the solid component from the above figures was shaped in a proper way to withstand loads and constrains. For the particular dimensions of the object the loads and constraints what we have given is safe.
The design optimization has been has been carried out in two software which is HYPERMESH and CATIA. Initially the optimization was carried out in Hyper Mesh because meshing plays an important role in analysing the model, if the meshing is not proper than the design of the model can leads to failure. An each of the optimization is possible to model it in Hyper Mesh. Any results of the optimization are available to see in Hyper View. This can help an engineer to better know of the new problem and resolve it.
CATIA is designing software it is fully compatible it has the capability to design a 3D solid. Today, nearly all products are designed on computers. Computers are even designed on computers. CATIA plays a major role in the design process. Architects are now using CATIA. It is used by the automotive and aerospace industries for automobile and aircraft product and tooling design. There are thousands of companies the world over using CATIA. For every company that uses CATIA for product design, there are hundreds of suppliers to those companies that also use CATIA.
Thus, the final weight of the product was different than it has been got from Hyper Mesh. Again we have analyzed the final design using Hyper Mesh again.
Thus, Hyper Mesh does not give a complete product but suggest only the way of the future shape solution. It is still important that an engineer has to control the design development and make it suitable for chosen manufacture path and any other aspects that have influence for a final project.