Detailed procedures for the production of composite materials using cement particles as filler materials in a polypropylene matrix, followed by an injection molding process, are described. The mechanical properties of the composite materials are evaluated on an Instron universal testing machine, where the experiments are performed according to the ASTM D638 standard.
Chapter 3 Investigation and Evaluation of Mechanical Properties of Fabricated Composite Materials
Chapter 4 Design and Fabrication of Composite Material Spur Gear
Chapter 5 Dynamic Performance Evaluation and Assessment of Wear Characteristics of Composite Material Spur Gear
Chapter 6 Investigation and Study of Vibration and Mechanical Properties of the Composite Materials and its Sandwich
Chapter 7 Conclusions and Future Scopes
Introduction
Examples of natural composite materials such as wood, bone and teeth are also composed of two or more components. Composite materials are much cheaper than metallic materials, but sometimes the incorporation of filler material into the matrix makes them more expensive.
Polypropylene as a Matrix
However, very few works have been carried out where Portland pozzolana cement (PPC) is used as a filler material in the polymer matrix. However, so far very limited works have been carried out addressing the design and development of low-cost polymeric composite materials suitable for industrial needs that include PPC as a filler material.
Inorganic Filler Particles
The main advantage of polypropylene is the recyclability of the polymer, which becomes a huge interest for industrializations. Polypropylene has found widespread applications in various fields such as civil construction, automotive, sporting goods, household, textile and chemical industries, electrical and biomedical applications, and marine construction.
Portland Pozzolana Cement as a Filler Material
Medvešček et al. (2006) demonstrated that the hydration of Portland cement clinker minerals is essentially their reaction with water, yielding a complex microstructure of variable composition. However, 24-hour cement hydration does not show a significant difference from the non-hydrated sample (Bishop et al., 2003).
Dispersion of Filler Materials into Matrix
Sennett et al., (2003) have reported dispersions of MWNTs in polycarbonate matrix by mixing in a twin-screw conical extruder followed by fiber spinning apparatus. Similarly, Bikiaris et al., (2008) also demonstrated the technique of dispersing MWNTs in polypropylene matrix by melt mixing in a HaakeeBuchler Reomixer (model 600).
Compounding and Fabrication of Composites
Using this technique, the dispersion of the filler takes place in the molten state of the polymer. Manufacturing: One of the leading techniques for manufacturing the polymer composite is injection molding technique.
Brief Overview on Polymeric Composite Materials
The purpose of the mixing process is usually to achieve a standardized dispersion of the minor component in the main phase. Therefore, dispersion of the filler materials and its subsequent effect on the composite materials serves the purpose of characterizing the polymer composites.
Characterizations and Structural Analysis of Composites
Choi et al., (2006) reported the observation of multiwall carbon nanotube (MWNT)/polysulfone (PSf) blend membranes. Dong et al. (2008) also reported on polypropylene/organoclay nanocomposites after conducting experiments such as X-ray diffraction (XRD), SEM, TEM and dynamic mechanical analysis (DMA).
Mechanical Properties of Composites
They also observed that the storage modulus of the composite gradually increases with the increase in the loading percentages of SWNTs. And for DMA tests, they reported that the storage modulus of the materials increases significantly with the addition of MWNTs.
Fatigue Behavior of Polymeric Composite Materials
The nanocomposites exhibited a smaller contact fatigue life at high rolling speeds even at low stress levels. At high contact stress, corresponding to the load of 225N at 2000 rpm, the sample lasted only about 0.17 million cycles, which is low compared to the lifetime of samples tested at low load and rolling speed.
Manufacturing of Non-metallic Composite Gear
Manjunatha et al., (2010) reported on the tensile fatigue behavior of silica nanoparticle modified glass fiber reinforced epoxy composite. In addition, numerous models have been developed for different gear systems to correlate the dynamic behavior of gears with various aspects such as quasi-static surface wear, wear depth, stress analysis and nonlinear contact deformation analysis using Hertz's cylinder contact theorem (Ivana et al., 2009; Sunil et al., 2010; Savage et al., 1986; Abbes et al., 2011; Ding, 2007; Draˇca, 2006).
Performance Analysis of Non-metallic Composite Gear
Similar to the composite material equipment, the steel gear was also subjected to APDL (ANSYS Parametric Design Language) test to investigate its performance. It is observed that for an applied torque of 150 Nm and a speed of 2000 rpm, the contact surface temperature rises to 93ºC even with proper lubrication (Jie et al., 2013).
Damping Characteristics of Polymeric Composites
When the temperature was increased to 140 °C, the loss modulus of the nanocomposite remained practically constant, while one of the matrices dropped to a negligible value. Furthermore, Kordani et al. (2010) showed that the damping properties of a CNT/epoxy composite beam differ significantly between samples with and without nanotubes.
Effects of Crack on Performance of Composite Materials
In addition, Auad et al., (2009) found that nanocomposites containing SWNTs or MWNTs where, high damping can be achieved by taking advantage of the weak bonding and interfacial friction between the individual nanotubes and the matrix. The maximum damping ratio of the 0.5 wt% SWNTs specimen is much higher than that of the 0.5 wt% MWCNT specimens and the regular specimens.
Application of Composite Materials
Ostachowicz and Krawczuk (1991) modeled the effect of cracking on the natural frequencies of a cantilever beam. Friswell and Penny (2002) investigated the crack identification for structural health monitoring and its remedy.
Motivation and Scope
In addition, fabricated composite materials are subjected to thermomechanical analysis (TMA), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) testing to understand the thermal stability and fire retardant properties of the fabricated thermoplastic composite materials. A direct performance analysis of the fabricated composite gear was carried out to evaluate its load-bearing capacity.
Objectives and Methodology
Modification of the dynamic test rig setup to study the dynamic performance of a tool equipped with a web-based infrared camera to monitor the surface temperature while driving. Experimentation and investigation of vibration characteristics on the impact of cracks in the manufactured composite cantilever beam.
Organization of the Thesis
In chapter 3, the characterizations and evaluation of the mechanical properties of composite materials are presented. It is essential to study the damping characteristics of composite materials suitable for structural and automotive applications.
Introduction
The Rheological properties of the composite materials are also investigated to find out the rate of change of viscosity of the composite materials with respect to temperature.
Materials and Methods
A schematic configuration of the injection molding setup is shown in Figure 2.2, while Figure 2.3 shows the original injection molding machine setup (JTS 40, TEXAIR-Plastics. & Hydraulics, Coimbatore, India). A step-by-step flow diagram for the manufacture of a cement-reinforced composite gear is shown in Figure 2.4.
X-ray Diffraction Analysis of the Composite Materials
Since, the main peaks of cement particles are absent in the diffraction patterns of the composites, which reveal the possible exfoliation of cement particles in the polypropylene matrix. Thus, X-ray diffraction patterns are highlighting the fact that the addition of cement particles in different amounts does not affect the crystallographic nature of polypropylene.
Investigation on Effect of Temperature on Composite Materials
It is also observed that the melting points of the composite samples are significantly affected by the presence of cement particles. The fact is attributed that the addition of cement particles significantly improved the thermal stability of the composite.
Thermomechanical Analysis (TMA)
This occurs due to decrease in the viscosity of the composite materials with the percentage increase of filler materials. Similarly, Figure 2.15 shows the coefficient of thermal expansion and observed to be decreasing as the cement loading percentage decreases.
Nanoindentation Test
This means that from the start of the unloading slope, the conventional elastic indentation stiffness is calculated (Wong et al., 2006). The elastic modulus of the sample can be derived from the initial release contact stiffness (S).
Raman Spectroscopy
As illustrated in Figure 2.21(b), the spectrum of cement-filled composites shows clear peaks at different wavenumbers, which is not inconsistent with peaks of cement as seen in the reference (Lackhoff et al., 2003). Since the intensity of the band increases at 810 cm-1 and 844 cm-1, this is evidence of the degree of crystallinity increasing in both the neat polypropylene and its composites (Arruebarrena et al., 1995).
FT-IR Analysis
The FT-IR spectra of a sample of polypropylene and its cement-based composites are analyzed and shown in Figure 2.24. However, the most significant difference is between the FT-IR spectra of pristine polypropylene and its cement-based composites, as seen in the 2840–2965 cm−1 region, where various CH2 peaks increased as the cement content increased.
AFM- Analysis and Surface Roughness
AFM image of 5% cement-reinforced composite shows well-structured morphology that also confirms that the cement surfaces are oriented parallel to the outer surface. It is thus concluded that higher cement content gives less ordered structures, predicting the less exfoliation of cement particles in the polypropylene matrix, e.g. for 10% and 15% cement-reinforced composite materials.
Rheological Behavior of Composite Materials
These investigations clearly show a dependence of shear viscosity versus shear rate at fixed temperature (200°C). At fixed temperature, the shear viscosity of pure polypropylene and its compounds decreases with increasing shear rate.
Summary
The AFM results show that increasing the amount of filler gives less exfoliation and less ordering of the structure; thus, it results in higher surface roughness of the composite materials. Well-interacted/exfoliated cement-reinforced polypropylene composite materials show well-structured and oriented composite morphology.
Introduction
Tensile Mechanical Behavior of the Composites with Circular Notches
The analysis showed that the breaking work is a function of the ratio between the diameter of the circular notch and the width of the specimen, as shown in Figure 3.3. The broken surface of the sample is prepared with a gold coating (because the composite is non-conductive) and examined under high voltage (10 kV) with 500x magnification.
Short-term Fatigue and Bending Analysis
The results show that the deformation behavior of the composite sample depends on the loading conditions and the selected cycle. This is considered to be the reason that the service life of the composite specimen strongly depends on the TH load.
Theoretical Modeling to Predict the Elastic Modulus of the Composites
As shown in Figure 3.13(a), the optimal aspect ratio of the filler materials is calculated as 213 when the modulus is nearly saturated. From Figure 3.13(a), the optimal aspect ratio of the filler materials is also calculated and approximately 213 when the modulus.
Summary
Furthermore, previous studies show that few works have been carried out to evaluate the dynamic mechanical properties of the composite materials used to manufacture gears. Moreover, few works deal with the failure analysis and the resulting topographical structures of the composite materials.
Manufacturing of Composite Spur Gear
Cement-coated polypropylene granules are then collected in a tray and prepared to be fed into the injection molding machine. Before the processed, cement-coated granules are fed into the injection molding machine, they are dried in the injection molding hopper for 2 hours at 80ºC.
Experimental Study: Optimization of Gear Materials
The tensile modulus of composite gear materials increases with an increase in the loading of cement particles (% wt) in the polypropylene matrix. To define the suitable material for the gear, the specific strain energy of polypropylene materials filled with cement particles is taken into account.
Cement content (wt%)
Gear Tooth Performance under Loading
Detailed schematic configurations and specifications of the fabricated composite gears are shown in Figure 4.11 and Table 4.3, respectively. The representation of crack formation due to fatigue loading near the gear root region is shown in Figure 4.14.
Test rig
Tooth deflection under cyclic loading
Impact Test and Evaluation of Toughness
As shown in Figure 4.21, a direct impact load is applied to the spur gear tooth impact strength. On the other hand, the impact load is applied to the base of the gear as shown in Figure 4.22.
Theoretical Model of Stress Distribution along the Mating Surface of Gear Tooth
The meshing teeth of the gear are shown in the highlighted circle in Figure 4.25(a). The root fracture area of a 10% cement filled composite gear after testing is shown in Figure 4.33(a) and marked by a circle.
Summary
Introduction
Modification of Gear Test-rig and its Accessories
Figure 5.5(a) and (b) illustrates the jamming of a gear pair made of pure polypropylene and 10 wt.% cement reinforced composite. Initially, the mutual matching of the gear pair is carried out with the shafts using a bushing and an adjusting screw.
Effect of Heat and Performance Analysis
For all cases, the power transfer is done through the metal gear shaft, located along the center of the gear and connected to its collar. As the metal shaft passes through the gear collar, a higher temperature rise is observed in the gear collar portion.
Dynamic Performance Test of Gear with Single Crack
It is further noted that surface temperature change shoots up to 50% high at the speed of 2500 rpm compared to the surface temperature at speed of 1800 rpm as shown in the Figure 5.16(d). The contour of thermographs of single cracked gear pair is shown in the Figure 5.17 with respect to time with a speed of 1800 rpm.
Dynamic Performance of Multi Crack Gear
It is observed that the induced crack does not significantly affect the lateral surface temperature variation of the test gears. It is also noticeable that the surface temperature rises more significantly on the surface of the gear flanks.
Evaluation of Wear Characteristics
Similar effect can be observed in the case of abrasive wear as shown in Figure 5.27 (a) and (b). However, it can be observed from Figure 5.29 that 15% cement filled composite exhibits slightly more specific wear rate compared to 10% cement filled composite gear material.
Summary
In addition, it can be observed that the surface temperature of the gear pair is lower compared to the results reported in past research for other composite and metal gears. The weight loss due to wear of a composite tool is estimated by direct measurements at a specified load and operating condition.
Introduction
The time response and Fast Fourier Transform (FFT) analysis is performed and then the damping and loss factor of the materials is obtained. The composite material sandwich panel is manufactured where aluminum and galvanized iron (GI) sheets are used as skin material and cement reinforced polypropylene based composite material is used as core material.
Evaluation of Damping Properties
The vibration response of the 10% and 15% cement filled composite specimens are measured and the experimental results are used to evaluate the damping properties of the proposed composite specimens. The experimental test results and the achieved damping properties of the material are represented in Tables 6.6 and 6.7.
Damping and Forced Vibration Characteristics of Sandwich Panels
The average phase difference and damping ratio of all composite specimens are illustrated in Figure 6.14(a) and (b) together with pure polypropylene respectively. The forced vibration response of Al and GI skin composite sandwich beams are illustrated in Figure 6.15 and Figure 6.17 respectively.
