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INTRODUCTION Textile reinforced composites are used for a widerange of applications. The anisotropic nature of thecomposite parts extends the potential of conventionalmaterials; however, an educated design of the layersand fiber alignment are necessary to fulfill therequirements. Filament winding is the main methodto produce axially symmetrical body parts from com-posite materials. Winding angle of the layers is themain parameter to determine the mechanical proper-ties. Depending on the structural design and require-ments of the composite part, winding angle ischanged during the production. The filament anglesrespond with a delay to the changing machineparameters. The aim of this study is to determine thefilament angle functions analytically both for constantand changing machine settings on complex shapedmandrels. There are many studies which analyze the effects offilament angle on the mechanical properties. Spencerand Hull have shown that both the tensile and shearstrength depends on the winding angles [1]. Mistryhas studied the mechanical behavior in particularbending and compression stresses of filament woundcomposite structures under hydrostatic pressure.The effects of winding angle were shown both exper-imentally and via finite elements analysis. The opti-mum winding angle was around 80 degrees for thiscoupled stress condition [2]. Filament winding onconical shapes is important for the production ofaerodynamical composite structures. In the literatureno study is published on the temporary response of

filament angle to the changing machine velocity.Kessels and Akkerman have developed a numericalmethod to determine the local angles on complexshaped braided structures [3]. Zhang et al. have ana-lyzed the kinematical properties [4] and mechanicalproperties [5] of cylindrical braiding. Nishimoto et al.have developed an analytical method to predict theresponse of filaments on cylindrical braiding [6].

THEORETICAL APPROACHCylindrical mandrel In this section, the equations of angle formations willbe determined by starting with a simple cylindricalmandrel and the equations for complex shapes willbe derived from this model. The mechanism of windingangle formation for filament winding on a cylindricalmandrel with constant speeds is depicted in fig- ure 1.The tangential angle a of the filament is determinedby the cylinder radius r, angular velocity of the man-drel w0 and lateral velocity of the filament guide v0. u0 = r w0 (1)

r w0 a = tan–1 ( ) (2)v0

If the angular velocity w0 or the tangential velocity v0of the system is changed as a step function, it takestime for the filaments to adapt the new productionconditions. This can be called as unstationary state ofthe system between two stationary conditions. Afterthe new steady state is reached, the winding of fila-ments continues with constant angle.

Dynamic response of filament winding angle on complex shaped mandrelsDOI: 10.35530/IT.071.05.1717

AHMET REFAH TORUN

ABSTRACT – REZUMAT

Dynamic response of filament winding angle on complex shaped mandrels

Aerodynamic parts such as rocket nose and heat shield related composites are mainly produced with filament windingmachines. Winding angle of the reinforcement filament is the main parameter to determine the thermomechanicalproperties of the final composite part. The angle adjustments on the machine cause the temporary response of thefilaments. This study derives an analytical method to determine the real angle of the filaments on the mandrel.

Keywords: winding angle, filament winding, composite materials, conical parts, complex shape mandrels

Răspunsul dinamic al unghiului de înfășurare al filamentelor asupra poansoanelor cu forme complexe

Piesele aerodinamice, cum ar fi vârful rachetei și materialele compozite pentru scutul termic, sunt produse în principalcu mașini pentru înfășurarea filamentelor. Unghiul de înfășurare al filamentului de armare este principalul parametrupentru a determina proprietățile termomecanice ale piesei compozite finale. Reglajele unghiului pe mașină determinărăspunsul temporar al filamentelor. Acest studiu descrie o metodă analitică pentru a determina unghiul real alfilamentelor de pe poanson.

Cuvinte-cheie: unghi de înfășurare, înfășurarea filamentelor, materiale compozite, piese conice, poansoane cu formecomplexe

452industria textila 2020, vol. 71, no. 5˘

The system response forthe cylindrical filamentwinding to velocitychanges can be analyzedby dividing the cross sec-tion of the cylinder with small angles (figure 2).For every turning of , theinitial winding angle aiapproaches to the finalwinding angle af . In figure 2 on the rightside, the first differentialstep leads the filament togo to the point X2 insteadof point X1. In this case,the triangles Y2X2Z andY2OC are similar, there-fore:

|OC |  |X2Z | = (3)|Y2C | |ZY2 |

If the iterations of the Ypoints are numbered asai and ai+1, the equation 3can be constructed as:

453industria textila 2020, vol. 71, no. 5˘

Fig. 1. Cylindrical model of filament winding with constant speeds

Fig. 2. Cylindrical Angle response to the velocity change

|OC |     r  w0 Dt   = ; Da = ai+1 – ai (4)ai+1  ai – ai+1 + vf  Dt

After dividing the right hand side of the equation withDt:

|OC | Da Da da [ – + vf ] = ai+1 ; where = ; r  w0 Dt Dt dt

r  w0 (5)ai+1 = a(t) ; = tan afvf

|OC |   da   |OC |– = a(t) – →

r  w0 dt  tan af

da   – r  w0  dt→ ∫ = ∫

(6)

|OC | |OC |a(t) –  

tan af

The differential equation (equation 6) can be solvedby separating variables and integrating afterwards.

r  w0–  t|OC | |OC |

a(t) = C0 e + (7)tan af

The boundary values are:|OC | |OC |

a(0) =   ; a() =   (8)tan ai

tan af

After inserting boundary values into equation 7:a(t) = |OC |  [(tan ai)–1 – (tan af)–1]

r  w0–  t|OC | |OC |

e + (9)

tan af

The time dependent function of a(t) according to theposition change a(t) can be written as:

|OC |tan a(t) = (10)

a(t)r  w0–  t|OC |a(t) = tan–1 {[[(tan ai)–1 – (tan af)–1] e +

+ (tan af)–1]–1} (11)

Conical mandrelFilament winding on conical mandrels is used inmanufacturing of aerodynamic composite structuressuch as rocket nose. Due to the change of mandrelradius along the length of the mandrel, the circumfer-ential velocity of the filament changes as well. Fig -ure 3 demonstrates the main parameters of filamentwinding on a conical mandrel. The radius r of cone is changing linearly along thelength, which affects the circumferential velocity.Filament guide moves laterally with the velocity of v0,however, the tangential lateral velocity of vtan must beused to find the winding angle.

Lcos b = (12)√ (R – r0)2 + L2

Dr R – r0 = tan b =   (13)v0  t  L

R – r0Dr = v0  t  (14)L

R – r0r(t) = r0 + Dr = r0 + v0  t   (15)L

If the angular velocity w0 and the lateral velocity vtanare constant, the winding angle according to localaxis on surface is:

R – r0r(t)  w0

[ r0 + v0  t   ] w0Ltan a = = (16)v0 v0

If the lateral velocity v0 is not constant and changedas a step function to vf, then the differential equationsimilar to the equation 6 defines the time dependentresponse of the winding angle. The difference is;radius r is not constant any more as in equation 6,instead the expression in equation 15 must be used.Tangent af is also changing with time, but if the angleb is small, the change can be omitted and the tan afcan be taken as constant to solve the integral.

|OC | da |OC |– = a(t) – R – r0[r0 + vtanf  t             ]  w0  

dt tan af  (17)L

a(t) = |OC |  [(tan ai)–1 – (tan af)–1] w0 vtanf (R – r0) – [r0 t +  t 2] |OC ||OC | 2L e +

(18)

tan af

a(t) = tan–1 {[[(tan ai)–1 – (tan af)–1]

w0 vtanf (R – r0)– [r0 t +  t 2]|OC | 2L e + (tan af)–1 ]–1 }(19)

In equation vtanf is the final tangential lateral velocityafter the change of lateral velocity. The initial windingangle ai and final winding angle af are found accord-ing to equation 16 as followed in equation 20 and 21.

R – r0[r0 + v0 t             ]  w0Lai (t) = tan–1 {   } (20)vtani

R – r0[r0 + vf  t             ]  w0Laf (t) = tan–1 {   } (21)vtanf

454industria textila 2020, vol. 71, no. 5˘

Paraboloid mandrelParaboloid mandrels can be used asheat shield or aerodynamic nosepart for supersonic vehicles. Suchas the approach of conical mandrelsis derived from the cylindrical equa-tions, same approach can be usedto derive the paraboloid equations.The differential equation (equation6) is taken and the radius expres-sion of paraboloid is integrated, andthen the equation is solved. Figure 4shows the main parameters ofparaboloid filament winding.

Fig. 3. Parameters on conical filament winding

Fig. 4. Parameters on paraboloid filament winding

For the case of constant lateral guide velocity v0 andangular velocity w0:

√x √v0r = y = ; x = v0∙ t; r(t) = ∙ √t (22)√a    √a

r ∙ w0 √v0 w0tan a = = ∙ √t ∙  (23)vtan √a vtan

The relation between the lateral filament guide veloc-ity v0 and the lateral velocity on the surface of theparaboloid vtan is defined by the derivative of theparabola equation.

√x dy 1y = ; = = tan b (24)

√a   dx 2√axv0vtan = (25)

cos b

Cos b in equation 25 can be found by drawing animaginary right triangle by using the tan b expressionfrom equation 24. The opposite edge of the right tri-angle is “1” and the adjacent edge is “2√ax ”. Theequation 25 becomes:

v0 ∙ 2√axvtan = (26)

√1 + 4ax

The radius equation (eq. 22) is inserted into the dif-ferential equation (eq. 6).

|OC |  da |OC |– ∙ = a(t) – (27)√v0

dt tan af ∙ √t ∙ w0√a

a(t) = |OC | ∙ [(tan ai)–1 – (tan af)–1] ∙  (28)2w0√vtanf  t 3/2

– |OC |∙ e 3 ∙ |OC | ∙ √a + tan af

a(t) = tan–1 {[[(tan ai)–1 – (tan af)–1]

2w0√vtanf  t 3/2

– e 3 ∙ |OC | ∙ √a + (tan af)–1 ]–1 }  (29)

The integration constants containing initial windingangle ai and final winding angle af can be calculatedvia equations 30 and 31.

√v0[  ∙ √t ] w0√aai (t) = tan–1   (30)vtani

√vf[  ∙ √t ] w0√aaf (t) = tan–1   (31)vtanf

RESULTS AND DISCUSSIONA cylindrical base model is assumed to see the timedependent response of filament winding angle tochanging lateral filament guide velocity. The radius ofthe cylinder r is 10 cm, angular velocity is 10 rad/s,distance of filament guide to the mandrel |OC| is 20cm, initial winding angle ai is 30° and the final wind-ing angle af is 60°. According to equation 11, figure 5shows how the filament winding angle responds to astep-wise changing of velocity.

Figure 6 shows the effect of increased angular veloc-ity from 10 rad/s of base model to 20 rad/s. Asexpected, the reaction of filament angle is faster andabout half of the time elapses to reach the final angle

compared to the base model of figure 5. Figure 7shows similarly the effect of increasing mandrelradius from 10 cm to 30 cm. Increasing of mandrelradius has the same accelerated reaction effect asthe increasing angular velocity.

If the filament angle changes 30°–60° of base modelis reversed to 60°–30°, the resulting curve is depictedin figure 8. The reaction time is a bit less comparedto 30°–60° change. Changing from a higher windingangle to lower takes slightly less time than vice versa. A conical mandrel is assumed with parameters ofnarrow end radius 10 cm, large end radius R 20 cm,mandrel length 100 cm, angular velocity w 10 rad/s,final tangential velocity vtanf 10 cm/s, distance of fila-ment guide to the mandrel |OC| 20 cm, initial windingangle ai 30° and the final winding angle af 60°.Figure 9 demonstrates the angle response curve, asthe conicity of the mandrel is not high, the curve lookssimilar to base model cylindrical mandrel, howeverthe calculated values are slightly different due to theequation 19.

455industria textila 2020, vol. 71, no. 5˘

Fig. 5. Change of filament winding angle on cylindricalmandrel: 30°–60° base model

Fig. 7. Change of filament winding angle on cylindricalmandrel: 30°–60° with increased radius r

Fig. 6. Change of filament winding angle oncylindrical mandrel: 30°–60° with increased angular

velocity w

Figure 10 shows the angle response curve on aparaboloid mandrel. The parameters are selectedlikewise to ease the comparison with previous mod-els of figures 5–9. The angular velocity w is 10 rad/s,final tangential velocity vtanf is 10 cm/s, distance of fil-ament guide to the mandrel |OC| is 20 cm, a is 2 atthe curve x = 2y2, initial winding angle ai is 30° andthe final winding angle af is 60°. According to equa-tion 29, figure 10 shows how the filament windingangle responds to a step-wise changing of velocity.The shape of the paraboloid flattens the reactioncurve of winding angle. The cylindrical, conical and paraboloid models allhave the common property of circular cross-section.

456industria textila 2020, vol. 71, no. 5˘

On the other hand, the elliptical mandrel yields achanging radius in the cross-section. The ellipticintegral of type 2 (equation 36) does not have an ana-lytical solution but it can only be approximated with aseries expansion (equation 41). Due to the approxi-mation, however, the time parameter “t” disappearsfrom the equation and the responding character can-not be seen, instead if the angle is changing from30°–60°, then the integral approaches to the meanvalue of 45°. Therefore, this method works only formandrels with circular cross-sections, for other typesof geometries a different approach is necessary to bedeveloped.

CONCLUSIONSAn analytical approach is derived for the filament wind-ing angle response on cylindrical, conical, paraboloidand elliptic cylindrical mandrels. Increasing of radiusand angular velocity decreases the time elapsed toreach the final winding angle. Independent of thetype of the mandrel, if the cross-section of the man-drel is circular, the method delivers applicableresults. On the other hand, the method is not applica-ble to mandrels with cross-sections other than circu-lar form because of the varying radius in the cross-section. A new method should be developed formandrels with cross-sections of noncircular forms.This method provides an analytical calculation ofwinding angle for filament wound textile reinforcedcomposites and structures.

REFERENCES

[1] Spencer, B., Hull, D., Effect of winding angle on the failure of filament wound pipe, In: Composites, 1978, 9, 4,263–271

[2] Mistry, J., Theoretical investigation into the effect of the winding angle of the fibres on the strength of filamentwound GRP pipes subjected to combined external pressure and axial compression, In: Composite Structures,1992, 20, 2, 83–90

[3] Kessels, J.F.A., Akkerman, R., Prediction of the yarn trajectories on complex braided preforms, In: Composites,Part A. Applied Science and Manufacturing, 2002, 33, 8, 1073–1081

[4] Zhang, Q., Beale, D., Broughton, R.M., Analysis of Circular Braiding Process, Part 1: Theoretical Investigation ofKinematics of the Circular Braiding Process, In: Journal of Manufacturing Science and Engineering, 1999, 121, 3,345–350

Fig. 8. Change of filament winding angle on cylindricalmandrel: 60°–30° base model

Fig. 9. Change of filament winding angle on conicalmandrel: 30°–60°

Fig. 10. Change of filament winding angle on paraboloidmandrel: 30°–60°

457industria textila 2020, vol. 71, no. 5˘

[5] Zhang, Q., Beale, D., Broughton, R.M., Adanur, S., Analysis of Circular Braiding Process, Part 2: MechanicsAnalysis of the Circular Braiding Process and Experiment, In: Journal of Manufacturing Science and Engineering,1999, 121, 3, 351–359

[6] Nishimoto, H., Ohtani, A., Nakai, A., Hamada, H., Prediction Method for Temporal Change in Fiber Orientation onCylindrical Braided Preforms, In: Textile Research Journal, 2009, 80, 9, 814–821

Author:

AHMET REFAH TORUN

Adana Alparslan Türkeş Science and Technology University, Faculty of Aerospace, Aerospace Engineering,

Çatalan Caddesi 201/1, 01250, Adana, Turkey

Corresponding author:

AHMET REFAH TORUN

e-mail: [email protected]

466industria textila 2020, vol. 71, no. 5˘

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[33] Spulbar, C., Birau, R., Emerging Research on Monetary Policy, Banking, and Financial Markets, IGI Global USA(formerly Idea Group Inc.), 2019, 322, ISBN13: 9781522592693, ISBN10: 1522592695, EISBN13:9781522592716, https://doi.org/10.4018/978-1-5225-9269-3

[34] Spulbar, C., Ejaz, A., Birau, R., Trivedi, J., Sustainable Investing Based on Momentum Strategies in Emerging StockMarkets: A Case Study for Bombay Stock Exchange (BSE) of India, In: Scientific Annals of Economics andBusiness, 2019, XX (X), 1–11 (tbd), https://doi.org/10.2478/saeb-2019-0029

Authors:

THONSE HAWALDAR IQBAL1, RAMONA BIRAU2, CRISTI SPULBAR3, BABITHA ROHIT4, PRAKASH PINTO4, THEKKEKUTT MATHUKUTTI RAJESHA5, FABRIZIO DI SCIORIO6

1College of Business Administration, Kingdom University, Bahraine-mail: [email protected];

2Faculty of Education Science, Law and Public Administration, Constantin Brancusi University of Targu Jiu, Romania3University of Craiova, Faculty of Economics and Business Administration, Craiova, Romania

e-mail: [email protected]. Joseph Engineering College, Vamanjoor, India

e-mail: [email protected], [email protected] & Quality Assurance Office, Kingdom University, Bahrain

e-mail: [email protected] of Campania Luigi Vanvitelli, Caserta, Italy

e-mail: [email protected]

Corresponding author:

RAMONA BIRAU e-mail: [email protected]

[35] Ejaz, A., Birau, R., Spulbar, C., Buda, R., Tenea, A.C., The impact of domestic portfolio diversification strategies inToronto stock exchange on Canadian textile manufacturing industry, Industria Textila, 2020, 71, 3, 215–222, http://doi.org/10.35530/IT.071.02.1696

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