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Composites and Fillers
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
Structural composites include laminas that can be sandwich or laminate. At times, there is confusion between which materials are sandwich or laminate laminas. Even so, here we will consider laminate composites as containing layers of material (generally considered the reinforcing agent) bound on one or both sides by an adhesive material. Generally, there are a number of layers of reinforcing material present with the distance between the layers being small compared to those present in sandwich composites. Plywood is an example of a sandwich laminar where layers or plies of wood are bound together using an adhesive such as one of the formaldehyde-related resins. Formica is an example of a laminate where paper, cloth, or other material is impregnated with the continuous phase material. Sandwich laminas are widely used in the textile industry where foam, plastic, and fabric are bound together into new textiles. Many electronic boards are laminas. Examples of laminates include surfaces for countertops and wall paneling.
Macromechanics of a Laminate
Published in Manoj Kumar Buragohain, Composite Structures, 2017
A laminate is an integral composite structural element that is made by bonding together a number of laminae. (Lamina, plural laminae, is a term more common in the context of mechanics of laminated composites. The term ply is more common in the context of processing of composites. We shall use both these terms as synonymous to each other.) Figure 5.1 shows a schematic representation of a laminate made up of six unidirectional laminae. Note that details of the laminae, other than the angle of orientation, have not been provided. Obviously, more details, such as ply thickness, ply material (carbon/epoxy, glass/epoxy, etc.), ply type (unidirectional, bidirectional, etc.), ply sequence, etc. are needed for complete description of a laminate. A number of ply combinations are possible that gives us different types of laminate configurations. Laminate description is generally given using codes. The usual practice for writing a laminate code is to write the angles separated by slashes inside a pair of square brackets. For example, let us consider the laminate shown below:
Properties and applications of engineering materials
Published in Alan Darbyshire, Charles Gibson, Mechanical Engineering, 2023
Alan Darbyshire, Charles Gibson
Laminates made from a thermosetting polymer resin and a filler material are widely used for working surfaces in the home, in restaurants and in the workplace. Formica and melamine are probably the best-known trade names that come from the thermosetting resins used to make them. The filler material may be paper or cloth that is impregnated with resin and partly cured. That is to say that the cross-linking process has started but is not complete. Alternate layers are then stacked together and placed in a hot press. The heating allows the cross-linking to proceed within and between the layers and the pressure ensures that there are no cavities present. The laminates produced are hard wearing, tough, heat resistant and resistant to staining.
UHMWPE textiles and composites
Published in Textile Progress, 2022
Ashraf Nawaz Khan, Mohit Gupta, Puneet Mahajan, Apurba Das, R. Alagirusamy
UHMWPE laminates are considered to be state-of-the-art materials specifically designed for ballistic impact-protection applications. A lot of research has been presented in the last two decades as the material has demonstrated its potental for use in body armour. These laminates behave differently compared with the aramid and other conventional high-performance fabrics due to their different failure mechanisms. The differences are observed due to several factors such as lower shear strengths, low interlaminar fracture toughness, and higher breaking strengths of fibres. Different shapes of projectile invoke different penetration and failure mechanisms. The fibres in these laminates do not break easily compared to glass and carbon but the laminates bulge out comparatively more than conventional fibres. Thin laminates are generally used in body armours whereas thicker sections find their use in vehicle armour. Thin and thick sections behave quite differently under the impact. The thicker sections involve more-complex failure mechanisms with the transition. Moreover, these laminates cannot be used for very high-temperature applications. Soft body armour is made of multiple layers of high-performance fabrics which in comparison to hard body armours provide less-restricted mobilisation for the wearer but are used for lower-threat protection compared to hard ones.
A higher order theory for functionally graded shells
Published in Mechanics of Advanced Materials and Structures, 2020
Laminated composites are usually used in various engineering structures. In traditional laminated composite structures, elastic, and homogeneous laminas are bonded together to obtain desirable mechanical properties [1]. Unfortunately, the high change in the material properties transversally the interface between different materials can result in large interlaminar stresses, which can initiate delamination or interface cracking. Efficient way to avoid this disadvantage is to use FGMs in which the material properties vary continuously from one side to another. This can be done by gradually changing the volume fraction of the compound materials, in the thickness direction of the beams, plates, and shells. In contrast to traditional laminates, the stress distributions in the FGMs are rather smooth. This is the main reason why the FG thin-walled structures, such as plates and shells, have many applications in many field of sciences and engineering, such as in mechanical (reactor vessels, turbines, etc.), in civil (bridges, industrial structures, etc.), in aerospace (aircrafts, rockets, etc.) engineering, and in micro- and nanotechnology (microchips, sensors, actuators, etc.) [3–9].
An investigation into the flexural and drawing behaviors of GFRP-based fiber–metal laminate
Published in Mechanics of Advanced Materials and Structures, 2018
Ali Rajabi, Mehran Kadkhodayan, Sadegh Ghanei
One of the most popular composite materials, known as fiber–metal laminate (FML), is used in industries to develop lightweight structures. These laminates gather the good properties of metals, such as ductility, impact, damage tolerances and surface finish with the advantages of fiber composite materials, such as high-specific strength, high-specific stiffness, good corrosion and fatigue resistance. These excellent properties convert them to a good substitute for metal structures, especially in automotive and aerospace industries.