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Fabrication of Composites
Published in Shishir Sinha, G. L. Devnani, Natural Fiber Composites, 2022
Ishan Srivastava, G. L. Devnani, Shishir Sinha
Sheet molding compound or sheet molding composite is a fiber-reinforced thermoset material. It is a compression-molded compound, which is implemented in places where higher mechanical strength materials are needed. SMC consists of reinforced fiber, polymer resin, catalysts, inert fillers, stabilizers, and other additives. It has hefty dielectric properties that make it one of the best electrical insulators. The SMC can easily be molded into complex geometries. Therefore, it has a very wide scope of implementation. SMC is made up of glass fiber, liquid thermosetting polyester resin, mineral fillers such as slate (or calcium carbonate), inhibitors, catalysts, release agents and film;, the thickening agent is processed into malleable sheets. Figure 6.7 shows the preparation of a sheet molding compound.
Manufacturing Techniques
Published in Sumit Sharma, Composite Materials, 2021
There are some common PMCs that do not contain long, continuous fibers; hence, we describe them separately in this section. Sheet molding compound (SMC) is the name given to a composite that consists of a polyester resin containing short glass fibers plus some additives called fillers. The additives generally consist of fine calcium carbonate particles and mica flakes. Sometimes calcium carbonate powder is substituted by hollow glass microspheres, which results in a lower density, but makes it more expensive. Figure 3.14 shows a schematic of the SMC processing. Polyester resin can be replaced by vinyl ester to further reduce the weight, but again with a cost penalty. SMC is used in making some auto body parts, such as bumper beams, radiator support panels, and many others. It has been used in the Corvette sports car for many decades. Polypropylene resin can be reinforced with calcium carbonate particles, mica flakes, or glass fibers. Such composites, though structurally not as important as, say, carb on fiber/epoxy composites, do show improved mechanical properties vis-a`-vis unreinforced resin. Characteristics such as strength, stiffness, and service temperature are improved. These materials are used in automotive parts, appliances, electrical components, and so forth.
Conventional Processing of Polymer Matrix Composites
Published in Sanjay Mavinkere Rangappa, Jyotishkumar Parameswaranpillai, Suchart Siengchin, Lothar Kroll, Lightweight Polymer Composite Structures, 2020
M.K. Singh, N. Verma, S. Zafar
The SMC technique is used to manufacture various products from different industries e.g., bonnet of automobile, electrical and electronics components, structural components, furniture, sanitary ware, etc. In addition to the above applications, it is also used to manufacture baths, arenas, spas, cinemas, and stadium seating.
Effect of fiber length on the tensile strength of unidirectionally arrayed chopped strands
Published in Advanced Composite Materials, 2020
Application of composite materials of which fiber bundles are cut into lengths of several centimeters such as Sheet Molding Compound (SMC) is gaining popularity due to their excellent formability. The authors proposes a concept of a prepreg sheet material called Unidirectionally Arrayed Chopped Strands (UACS) in which fiber bundles of a predetermined length are aligned unidirectionally by introducing systematic slits into an unidirectional prepreg with aligned continuous fibers. This material demonstrates dramatic improvement in strength and minimal dispersion of fibers in the laminate material compared to SMC fabricated composite [1–6]. The structure of this UACS laminated material, even though it varies in scale, simulates the structures of bones and teeth having a staggered lamination of hard inorganic plates bounded by a protein matrix and addresses both considerably high strength and toughness [7,8].
Sliding mode control of power converters: DC/DC converters
Published in International Journal of Control, 2018
Yazan M. Alsmadi, Vadim Utkin, Mohammed A. Haj-ahmed, Longya Xu
Due to its order reduction property, good dynamic performance and low sensitivity to disturbances and plant parameter variations, sliding mode control (SMC) has been the method of choice for handling nonlinear systems with uncertain dynamics and disturbances. Moreover, this control methodology reduces the complexity of feedback control design since the system is decoupled into independent lower dimensional subsystems (Utkin, 1992; Utkin, Guldner, & Shi, 2009). Because of these properties, SMC has a wide range of applications in the areas of electric motors, power systems, power electronics, robotics, aviation and automotive control (Bartolini, Fridman, Pisano, & Usai, 2008; Utkin, 1978 , 1992; Utkin et al., 2009).
Recent progress in 4D printed energy-absorbing metamaterials and structures
Published in Virtual and Physical Prototyping, 2023
Chukwuemeke William Isaac, Fabian Duddeck
To further accentuate the improved mechanical performance of SMC structure over SMP structures, Liu et al. (2023) blended two SMPs (i.e. PLA and TPU) with iron oxide () particles using FDM 3D printer to realise a 4D printed re-entrant honeycomb structure. Before the realisation of these auxetic structures, some rectangular shapes specimen composed of PLA/TPU/ SMC were 3D printed and their SME were investigated. The PLA crystalline region was the fixing phase while the amorphous or non-crystalline region of the SMC was the switching phase that enabled the formation of temporary shapes. That is, at temperature above the , the mobility of the non-crystalline region of PLA was reinforced and a temporary deformation shape was realised. Moreover, the blending of small amount of TPU to the PLA acted as a toughness agent which prevented the PLA from irreversible damage during deformation and shape recoverability. Further, the addition of different particles helped to trigger the magnetic field for SME. Thus, SMC have higher capacity than the SMP in terms of improved mechanical performance and as such has promising potential in device where high load carrying capacity is desired. Moreover, for SMC containing fibre reinforcement, it was shown that the fibre contents had significant effect on the tensile properties (Dong et al. 2021a). However, to prevent the reduction of shape memory performance for SMC with fibre incorporation, careful design and optimisation should be carried out by regulating both the printing process parameters and fibre contents.