TENSILE TEST ARAMID PROER GRIPS DEVELOPMENT THROUGH REVERSE ENGINEERING TECHNIQUES ASSISTED BY RAPID...
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TENSILE TEST ARAMID PROPER GRIPS DEVELOPMENT THROUGH REVERSE ENGINEERING TECHNIQUES ASSISTED BY RAPID PROTOTYPING D’CASTRO, Eduardo F.S. Universidade Federal de Campina Grande. Rua Aprígio Veloso, 882 – Bairro Universitário. Campina Grande-PB-BRA. [email protected] AMORIM JR., Wanderley F. Universidade Federal de Campina Grande. Rua Aprígio Veloso, 882 – Bairro Universitário. Campina Grande-PB-BRA. [email protected] Abstract. The aramid tensile tests are important in bullet proof vests conception, in this point this tests give variables capable to determine mechanical properties of many ballistic materials. These aramid tensile tests are complex and have tendencies to failure, in this way it requires test proper grips. These grips are expensive products, difficult to be found and lengthy in delivery process, once it is an imported product and there are not aramid manufacturing in Brazil. This paper describes an aramid tensile test proper grips design development through, and, at the same time are shown results with proper grips use, improving the successful tests number comparing to data provided by other test techniques and similar grips in the market. The previous prototype (in photocurable resin) were produced and with those one can be able to produce the original product. Keywords: reverse engineering, rapid prototyping, product engineering, CARE, CAD/CAM. 1. INTRODUCTION Aramid yarns usually components of ballistic vests and its mechanical properties are very important to vests production. These yarns are sintetically prepared and stronger than carbon steel and its hardness are superior to glass. This properties becomes tensile test complexes with slippage between the claws. In this point this paper intend shows the development process and its methodology, based on Reverse Engineering Properties assisted by Computer (CARE) and Rapid Prototyping, photography and Numerical Methods, finalizing in aramid yarns tensile test proper grips according with ASTM standards. 2. THEORIC FUNDAMENTATION 2.1 Aramid yarns tensile tests According with (Xuesen, 2006), there are many issues in aramid tensile tests with regular grips like clamp ruptures and slippage because stress concentrator grips caused by excess tension clamps. In this same path, it’s
Transcript of TENSILE TEST ARAMID PROER GRIPS DEVELOPMENT THROUGH REVERSE ENGINEERING TECHNIQUES ASSISTED BY RAPID...
TENSILE TEST ARAMID PROPER GRIPS DEVELOPMENT THROUGHREVERSE ENGINEERING TECHNIQUES ASSISTED BY RAPID
PROTOTYPING
D’CASTRO, Eduardo F.S. Universidade Federal de Campina Grande. Rua Aprígio Veloso, 882 – Bairro Universitário. Campina [email protected]
AMORIM JR., Wanderley F. Universidade Federal de Campina Grande. Rua Aprígio Veloso, 882 – Bairro Universitário. Campina [email protected]
Abstract. The aramid tensile tests are important in bullet proof vests conception, in this point this tests givevariables capable to determine mechanical properties of many ballistic materials. These aramid tensile testsare complex and have tendencies to failure, in this way it requires test proper grips. These grips areexpensive products, difficult to be found and lengthy in delivery process, once it is an imported product andthere are not aramid manufacturing in Brazil. This paper describes an aramid tensile test proper gripsdesign development through, and, at the same time are shown results with proper grips use, improving thesuccessful tests number comparing to data provided by other test techniques and similar grips in themarket. The previous prototype (in photocurable resin) were produced and with those one can be able toproduce the original product.Keywords: reverse engineering, rapid prototyping, product engineering, CARE, CAD/CAM.
1. INTRODUCTION
Aramid yarns usually components of ballistic vests and its mechanicalproperties are very important to vests production. These yarns are sinteticallyprepared and stronger than carbon steel and its hardness are superior to glass.This properties becomes tensile test complexes with slippage between the claws.In this point this paper intend shows the development process and itsmethodology, based on Reverse Engineering Properties assisted by Computer (CARE)and Rapid Prototyping, photography and Numerical Methods, finalizing in aramidyarns tensile test proper grips according with ASTM standards.
2. THEORIC FUNDAMENTATION
2.1 Aramid yarns tensile tests
According with (Xuesen, 2006), there are many issues in aramid tensiletests with regular grips like clamp ruptures and slippage because stressconcentrator grips caused by excess tension clamps. In this same path, it’s
D’CASTRO and AMORIM Jr. Tensile test aramid proper grips development through reverse engineering techniques assisted by rapid prototyping
another issue reach axial regularity between every yarn filaments. Additionallyresearchers like recent work (Xuesen, 2006), (Bernardi, 2003), (Boukouvalas,2007), (Nilakantan et al, 2010), had this issues with no standard aramid yarnstensile tests, like described above.
To overcome this is issues the standard ASTM D7269 are used, and the gripsmust be in accordance with this standard and the Instron 5269 machinedimensions.
2.2. Design Methodology
To reach this goals in short time, was chosen Reverse Engineering methodsand techniques from recent work (Wang, 2011) and (Raja et al, 2008) adapted tothis grips design development with 3d model generation and numerical methodsfrom recent work (Wang, 2011) and (Chapra et al, 2010). Specially in ComputerAided Reverse Engineering (CARE) methods.
The big picture of Reverse Engineering process consists in final productdata collection from other manufacturers and optimize this one, electingstronger and weaker points in original design until development a better one.This methodology is over used in strategic sectors of industry mainly inelectronics and software, at last this methods are cheap and fast in thanstandard project methods.
3. MATERIALS AND METHODS
Was adopted the reverse engineering methodology, perhaps its adapted toabsence of a 3D scanner to generate a tridimensional CAD model. The developedmethodology uses pictures to absorbs dimensions and generates a volume usingnumerical methods (Pic.1).
22nd International Congress of Mechanical Engineering (COBEM 2013)November 3-7, 2013, Ribeirão Preto, SP, Brazil
Picture 1. Adapted Reverse Engineering method.
In accordance to de flowchart above, the method are defined in sixsteps.
Photograph: it’s the method first step. From a picture with one knowdimension at least, and maybe taked by operator or any picture from aproduct – like catalogs images – that will be pass by a reverseengineering process.
Point Assigning: this step is based in geometric assigning process ofscanning, very common in CARE. Basic, consists in attribute points to partgeometry key-points.
Calculates Ratio: in this phase the reverse engineer maybe uses computerresources or not. Basically is a quotient between the know real dimensionand this same dimension measured in picture. Anyway, to justify CARE isfaster and less tedious use any software feature to automatically convertall dimensions to real scale.
Link points: just link geometry key-points to obtain part boundaries assolid piece when use a extrusion feature of any CAD software.
Extrusion: extrude the part geometry boundaries as well. Refine Geometry: this step requires some experience in 3D project as solid
mechanics. In this task the operator will close the unclosed boundaries,
D’CASTRO and AMORIM Jr. Tensile test aramid proper grips development through reverse engineering techniques assisted by rapid prototyping
attribute tangent line in curves to decrease stress concentration in anypoints. Additionally holes, threads, recesses and chamfers not assigned ingeometry boundaries determined in point assigning as well.
Print Model: finally the haptic evaluation is made by operator in aphysical model from a 3D Printer and, in case of any process fail,corrections, discussions and client or user evaluation. This final modelmaybe functional or conceptual as reverse engineering and user desires.
4. RESULTS AND DISCUSSION
The first step consists in generate a point cloud in a plane assigningpoints over the object dimension extremes in the picture then calculates a ratiobetween the real dimension (expresses in datasheet or measured in real object)this steps involves “photograph”, “point assigning” and “calculates ratio” inflowchart (Pic. 1). In this case was used a catalog picture, its dimensionoriginal data from datasheet and Autodesk Inventor 2013 student’s versionsoftware CAD to assigning points, link, extrusion and refine that geometry (Pic.2).
Picture 2. Point assigning in proper grips picture.
The second step (“link points” in flowchart) is link the points in pointcloud using CAD software features like “line” and “spline” or using numericalmethods to absorbs a function and uses “draw function curve” feature. To linkpoints generating a curve and its function is used the La Grange InterpolationMethod (Eq.1), described by the equation in Wolfram Alpha Mathemathica 7:
(1)
The third step is described as “extrusion”, exactly like CAD featuresusually. This step is processed when every boundary are closed like a polygon(Pic. 3).
22nd International Congress of Mechanical Engineering (COBEM 2013)November 3-7, 2013, Ribeirão Preto, SP, Brazil
Picture 3 linked points forming a bounding sketch.
The next step is “refine geometry” using a CAD program to draw invisibledetails in picture deducted from other material like catalogs and technicalspecifications (Pic. 4), insert chamfers, holes, etc. For example, the bollardguidance to yarns in this proper grips was drew from the 4mm limit to yarnsdiameter information described in Instron aramid tensile test proper gripscatalog.
Picture 4. Extruded and refined geometry.
The next step is “print the model” to design team analyze the final productits functionality, ergonomics, aesthetics and other details not seen in designprocess. In this case was used a Objet/Stratasys connex350 (Pic. 5) in 30µmresolution and cleaned in a Balco WaterJet Cleaning Unit (Pic. 5), and after with a 2:8caustic soda and water solution bath to removed support material (Pic. 6), infine details.
D’CASTRO and AMORIM Jr. Tensile test aramid proper grips development through reverse engineering techniques assisted by rapid prototyping
Picture 5. 3D printer and waterjet unit.
Picture 6. Printed prototype in 3D printer.
The final step is analyzing the final product features, apply modifications –if necessary- and print again, or repeat the flow in flowchart until everythingis in accordance with design goals.
Picture 8. Cleaned prototype in Waterjet.
22nd International Congress of Mechanical Engineering (COBEM 2013)November 3-7, 2013, Ribeirão Preto, SP, Brazil
The process final product is a 3D model prototype to evaluate ergonomics,functionality, dynamics, if the designs goals was reached, etc. In this methodwas obtained a 3D model printed and analyzes the prototype like in the tablethat follows:
Design Features Needoptimize?
Stress concentrators YesDimensional tolerances YesAxiality in tensile
test assemblyNo
Table 1. Design features analysed in prototype.
The cycle restarts refining smoothing geometry, dimensional tolerances ereducing mass quantity. After all, the prototype is useful and in accordancewith ASTM standards in a short time and dispensing huge researches and standarddesign steps.
5. CONCLUSIONS
The adopted adapted methodology enabled generates a 3D model without a3D scanner, making it possible a CARE process without huge andexpensive equipment in order of €R2,000.00 as a David-3D.
The rapid prototyping method enabled costs reduction with materials andproduction, optimizing the design and freeing small businesses fromhuge investments in wrong hard-tooling or corrections.
In qualitative evaluation and in terms of time and costs CARE, insteadwithout scanning equipment proofs rapid prototyping as strategicallyfactor in competitive field of project and business.
Its possible generates a 3D model of some objects without its physicalpresence by mathematical analysis of complexes curves and CARE.
6. ACKNOWLEDGEMENTS
Acknowledgements to BCA Ballistic Protection (São José dos Campos-SP) andNUTES (UEPB-Universidade Estadual da Paraíba).
7. REFERENCES
Wang, Wong. Reverse Enginnering: Technology of Reinvention. Taylor&FrancisGroup.Broken Sound Parkway, NW, USA, 2011.Raja, Vinesh.Reverse Engineering, an industrial perspective. Springer-VerlagLondon Limited. London, ING, 2008.Xuesen, Zeng. Numerical Analysis of Fabric Armour Under BallisticImpact.Cingapura. National University of Singapore, 2006.
D’CASTRO and AMORIM Jr. Tensile test aramid proper grips development through reverse engineering techniques assisted by rapid prototyping
Bernardi, Stefania Tesi. Avaliação do comportamento de materiais compósitosde matrizes cimentícias reforçadas com fibra de aramida Kevlar. Porto Alegre,UFRGS, 2003. Boukouvalas et Wiebeck, Nicolas T. e Hélio. Caracterização térmica de fios depoliaramida. in Polímeros: Ciência & Tecnologia, vol. 17, nº 4. P 284-288,2007. Mietti, Marco Antonio & Vendramento, Oduvaldo. Uso da prototipagem rápidacomo fator de competitividade. UNIP Journal. São Paulo, 2000.Nilakantan et al. Experimental evaluation and statiscal characterization of thestrength and strain energy density distribution of Kevlar KM2 yarns:exploring length-scale and eaving effects. In Journal of CompositesMaterials, 2010. Newark, Delaware, EUA, 2010.David Laserscanner. 11 February 2014, Homepage. David 3D solutions GbR. 11February 2014 < http://www.david-3d.com/ >.
