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Int. J. Mech. Eng. & Rob. Res. 2014 Sujeet Ganesh Kore et al., 2014

DESIGN AND ANALYSIS OF A MACHINE TOOLSTRUCTURE BASED ON STRUCTURAL BIONICS

Sujeet Ganesh Kore1*, M I Sakri2 and L N Karadi3

*Corresponding Author: Sujeet Ganesh Kore, sujeetkore@gmail.com

A structural bionic design process is systematically presented for lightweight mechanicalstructures. By mimicking biological excellent structural principles, the structure of lathe bed orthe stiffening ribs of a lathe bed were redesigned for better load-bearing efficiency. In this paper,a machine bed (Manufacturer: Indira Machine Tools Ltd.) is selected for the complete analysisfor static loads. Then investigation is carried out to reduce the weight of the machine bed,reduce the stress induced in the lathe bed and to reduce the displacement. In this work, the 3DCAD model for the existing bed model and the optimized bed model has been created by usingcommercial 3D modeling software SOLID EDGE V20. The analyses were carried out usingANSYS 13. The results were discussed.

Keywords: Lathe machine bed, Bionic structure, Design optimization, Ansys

INTRODUCTIONAfter several billion years of evolution, thestructures of organism in nature have excellentproperties and ingenious frames, whichprovide a large amount of innovativeprototypes and creative approaches for solvingengineering problems and improving designmethods. Structural bionic has become a newmethod for mechanical design, which hasmade great progress in intelligent robots,aircrafts, watercrafts, Micro Air Vehicle (MAV),bionic bulldozer blades and other structuraldesign fields (Chen et al., 2008; and Ren and

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Int. J. Mech. Eng. & Rob. Res. 2014

1 Department of Machine Design, BLDEA’S PGH College of Engineering and Technology, Bijapur 586103, Karnataka, India.2 Department of Automobile Engineering, BLDEA’S PGH College of Engineering and Technology, Bijapur 586103, Karnataka, India.3 Department of Mechanical Engineering, BLDEA’S PGH College of Engineering and Technology, Bijapur 586103, Karnataka, India.

Liang, 2010). In lightweight design, structuralbionic has created many inventions with highspecific stiffness and toughness (Junior andGuanabara, 2005). Ma et al. (2008) sedcomposite-foam-resin concrete sandwichstructures for precision machine tool column.Kim et al. (2006) suggested an innovativedesign method termed adaptive growthtechnique by studying the optimality andgrowth mechanism of branch systems innature. Pflug  et al. (2004) developedlightweight sandwich boards of honeycombcore, and it is useful to the automotive industry.

Research Paper

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Int. J. Mech. Eng. & Rob. Res. 2014 Sujeet Ganesh Kore et al., 2014

Based on bamboo’s mesostructure shape andits arrangement, Chen et al. (2008) designedthe bionic reinforcing frame of aircraft, whichincreased structural specific stiffness andstrength. Because of lacking of mature andscientific design theories, the application is notextensive. So it is necessary to study thedesign method and process systematically,which will be helpful for further bionicapplication. By mimicking biologicalstructures, we can achieve optimal designswith minimum energy and material. It issignificant for resources saving and long-termdevelopment of China, which is a bigmachinery manufacturing country. Then thetraditional manufacture process can beimproved and the “green products” will uselimited resources efficiently.

There are many biological structures withoutstanding performance in nature. They canuse minimum material and resource to buildoptimized structure without loosing strengthand stiffness, which inspires us to implementlightweight design with high SSE.

Many biological structures have highstrength, stiffness and anti-bendingdeformation ability with minimum weight, suchas bulrush, sorghum, corn, bamboo, bonesstems, etc. Their stems are characterized ascone-shaped column with many nodes and theircross-sections are hollow-core circle (Figure1). For example, bulrush (Figure 1a) andbamboo (Figure 1b) have high culms with manynodes. The cross-section (Figure 1a) ofbulrush includes a three-layered sandwichstructure formed by the outer and inner ring ofstrengthening tissue connected by wedge-shaped struts.

METHODOLOGYBecause bionic design is a multidisciplinaryscience that researches the principles,properties and mechanisms of natural systems(structures, processes, functions,organizations and interrelations), with the aimof applying in the development of new productsor solving technical problems. So it isnecessary to study a systematic method toprovide fundamental information, which canassist designers in searching for efficientsolutions in nature.

Structural bionic is a creative alternative formechanical design to learn from natural perfectand efficient structures. Based on thesuccessful bionic designs, the method ofstructural bionic design can be summarizedas shown in Figure 1. The design process isdivided in three stages:

Requirements Identification: Manystructural bionic designs come from designers’inspiration. Then the natural structuralcharacteristics can be mimicked, for examplelotus effect and self-cleaning surface. And

Figure 1: Photos of Biological Structures

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Int. J. Mech. Eng. & Rob. Res. 2014 Sujeet Ganesh Kore et al., 2014

technical requirements for improvement canalso excite natural structures research. Whenthe bionic requirements are identified,analogous structures must be selected forfunction and structure analysis.

FEM Analysis: Published articles and otherdocuments will assist designer to learn basicprinciples of biological structures. Butexperiments are necessary for detailedobservation and investigation. Then theprinciples ca be extracted and mathematicalmodels can be established. The modeling andFEM simulation can verify the effectiveness ofstructures. If the results are not satisfied, newbiological structures must be used.

Experiments Verification: If the simulationresults are satisfied, bionic models should befabricated for structural experiments. After thebionic effectiveness is validated, those

biological structures can be used for practicalapplication. Otherwise, another designprocedure should be carried out, until the mostreasonable structure is found. And bionicprinciples can be concluded.

Structural bionic design is one creativemethod by mimicking biological structuralprinciples. The design flowchart is reliable andeffective. FEM simulation and experimentsverif ication can be used for practicalapplication. The natural lightweight, hollow andsandwich structures can contribute to updatingconventional distribution of stiffening ribs.Structural parameters need furtheroptimization, which may achieve higherspecific stiffness.

MODELING OF LATHE BEDBefore redesigning, the existing bed is createdby part modeling and subjected to staticanalysis. In this project the existing bed istaken from the manufacturer by company nameINDIRA MACHINE TOOLS.

The major dimensions of the machine bedare as follows: Length = 1540 mm (in

Figure 2: Flowchart of Design Process

Figure 3: CAD Model of Existing Lathe Bed

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Int. J. Mech. Eng. & Rob. Res. 2014 Sujeet Ganesh Kore et al., 2014

Y-direction), Width = 246 mm (in X-direction),Height = 242 mm (in Z-direction) (total height).

STRUCTURALMODIFICATION OFMACHINE TOOL BEDIn nature there are many biological structureswith excellent performance, such as bamboos,bones, stems and leaf veins. They can use

minimum material and resource to buildoptimized structure without loosing strengthand stiffness, which inspire us a lot for bionicdesign. A typical application is “Bamboo” haspractical significance in lightweight design ofmachine tool structures. During growingperiod, plants or bones can adjust thematerials according to stress distribution. Thedangerous areas will be strengthened for

Figure 4: Meshing of Existing Model

Figure 5: Applying Boundary Conditionof Load 1000 N

Figure 6: Vonmesis Stress of LatheMachine Bed of Cast Iron

Figure 7: Modal Shape 1 of Lathe MachineBed of Cast Iron

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Int. J. Mech. Eng. & Rob. Res. 2014 Sujeet Ganesh Kore et al., 2014

damage prevention. And the optimal materialsdistribution will decrease the structural mass.Therefore by mimicking those characteristicsor principles, lightweight improvement may besatisfactory and encouraging.

The different modified machine bed asshown below:

Optimized Model (1)

Optimized Model (2)

Figure 8: CAD Model of Optimized Model(1) of Cast Iron

Figure 9: Vonmesis Stressof Optimized Model (1) of Cast Iron

with Same Boundary Conditions(i.e., Load of 1000 KN)

Figure 10: Modal Shape 1 of OptimizedModel (1) of Cast Iron

Figure 11: CAD Model of Optimized Model(2) of Cast Iron

Figure 12: Vonmesis Stress of OptimizedModel (2) of Cast iron with Same Boundary

Conditions (i.e., Load of 1000 KN)

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Int. J. Mech. Eng. & Rob. Res. 2014 Sujeet Ganesh Kore et al., 2014

RESULTS OF STATICSTRUCTURAL ANALYSISThe results of static structural analysis usingANSYS for Existing model as well as other twooptimized models are presented. The effectsof some other materials (St.steel & Al-Alloy)for these models are presented and also Massreduction on the machine bed is presented.

Figure 13: Modal Shape 1 of OptimizedModel (2) of Cast Iron

Cast Iron 307 257 276

St-Steel 334 281 300

Al-Alloy 118 99 106

Table 1: Comparison of Weight of LatheMachine Bed

Weight in (KG)

ExistingModel

OptimizedModel (1)

OptimizedModel (2)Materials

Cast Iron 20589 17622 14871

St-Steel 20403 17533 14716

Al-Alloy 20104 17423 14502

Table 2: Vonmesis Stress of LatheMachine Bed

Maximum Stress in (pa)

ExistingModel

OptimizedModel (1)

OptimizedModel (2)Materials

Cast Iron 0.1084 0.1287 0.1071

St-Steel 0.0593 0.0706 0.0586

Al-Alloy 0.1660 0.1976 0.1638

Table 3: Displacements of Lathe MachineBed

Displacements in (µm)

ExistingModel

OptimizedModel (1)

OptimizedModel (2)Materials

1 686.2 643.97 697.14

2 767.0 814.8 789.58

3 1206 1203.4 1396.5

4 1375 1540.3 1514.1

5 1700 1793.2 1917.2

6 1814 1914.8 2107.2

Table 4: Modal Analysis Resultsfor Cast Iron Materials

ExistingModel(Hz)

OptimizedModel (1)

(Hz)

OptimizedModel (2)

(Hz)

ModeShapes

1 883.5 828.46 895.75

2 998.9 1050.3 1018.2

3 1554 1550.9 1796.8

4 1772 1984.2 1950.7

5 2202 2322.9 2485.2

6 2343 2476.7 2720.1

Table 5: Modal Analysis Resultsfor Structural Steel Materials

ExistingModel(Hz)

OptimizedModel (1)

(Hz)

OptimizedModel (2)

(Hz)

ModeShapes

CONCLUSION• From the above results, the weight

optimization of lathe machine bed has beenachieved (Approximately 15%) for all thethree material, hence the manufacturingcost also has been reduced.

• The von-mises stress for Optimized model2 and Optimized model 3 has beenreduced. (Approximately 19%).

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Int. J. Mech. Eng. & Rob. Res. 2014 Sujeet Ganesh Kore et al., 2014

• The Natural frequency is also Improved (i.e.,increased) for Optimized models.

• From the above results, Optimized model2 selected as the best model due to lowstresses, low weight, less displacementsand high natural frequencies, when it iscompared with original model.

ACKNOWLEDGMENTI am extremely thankful to each and everyonewho have helped directly or indirectlyresponsible for successful completion ofproject work. Foremost I would like to expressour deep sense of gratitude to our belovedprincipal Dr. V P Huggi for providing necessaryfacilities.

I am extremely thankful to our Guide Dr. M ISakri and Prof. L N Karadi constantenthusiasm and watchable supervisionthroughout completion of project.

REFERENCES1. Chen P Y, Lin A Y M, Lin Y S, Seki Y,

Stokes A G, Peyras J, Olevsky E A, MeyersM A and McKittrick J (2008), “Structure and

Mechanical Properties of SelectedBiological Materials”, Journal of theMechanical Behavior of BiomedicalMaterials, Vol. 1, pp. 208-226.

2. Junior W K and Guanabara A S (2005),“Methodology for Product Design Basedon the Study of Bionics”, Materials andDesign, Vol. 26, pp. 149-155.

3. Kim D I, Jung S C, Lee J E and Chang SH (2006), “Parametric Study on Designof Composite-Foam-Resin ConcreteSandwich Structures for PrecisionMachine Tool Structures”, CompositeStructures, Vol. 75, pp. 408-414.

4. Ma J F, Chen W Y, Zhao L and Zhao D H(2008), “Elastic Buckling of BionicCylindrical Shells Based on Bamboo”,Journal of Bionic Engineering, Vol. 5,pp. 231-238.

5. Ren L Q and Liang Y H (2010), “BiologicalCouplings: Function, Characteristics andImplementation Mode”, Science in ChinaSeries Es: Technological Sciences,Vol. 53, pp. 379-387.