makes polymers more vulnerable to twisting under load.

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Torsional stiffness depends on the materials. Metals, which have a high shear modulus, inherently have high torsional stiffness. For example, steel has a shear modulus of 80 GPa and is useful in areas where torsional moments are high, such as drive shafts and machinery. The uniformity of metals prevents variations in the material's torsional stiffness, allowing it to provide predictable performance in situations that require high precision and high load capacity.

However, polymers have a relatively low shear modulus, ranging from 0.5 to 3 GPa, which results in low torsional stiffness. This characteristic

However, their flexibility and elasticity can be useful when a certain degree of deformation is allowed. For example, they are useful in flexible couplings. If we compare the torsional state of a metal rod and a polymer rod by applying the same torque, the angle is relatively larger in the latter. This proves the difference in torsional rigidity of these two materials.

In contrast, composites have the advantage of eu data having tunable characteristics, with torsional stiffness depending on the fiber and matrix materials. Although composites have high stiffness potential, these structures are known for their anisotropic behavior. This means that the stiffness depends on the direction of loading. Alignment of the reinforcing fibers is vital and requires precise orientation for optimal performance. Furthermore, torsional stiffness characteristics can also vary in heterogeneous materials such as composites and may not be consistent across all parts of the cross-section.

Table 1: Comparison of torsional stiffness of metals, polymers and composites
Material type Example of material Shear modulus (G) in GPa Polar moment of inertia (J)( ×10 -6 m 4 Torsional stiffness (GJ) In Nm 2 Relative density (kg/m³) Common applications
Metal Steel (AISI 1045) 80 5 400 7050 Drive shafts, gears, machine parts
Metal Aluminum (6061-T6) 26 4 104 2700 Aircraft components, automotive parts
Polymer Polyethylene (HDPE) 0.8 3 2.4 950 Pipes, flexible fittings
Polymer Polycarbonate (PC) 2.3 3.5 8.05 1200 Safety helmets, automotive glazing
Composite PRFC 100 6 600 1600 Aerospace components, high-performance sports equipment
Composite PRFC 25 4.5 112.5 1850 Marine components, automotive panels
Torsional stiffness in structural engineering
Torsional stiffness of skyscrapers and bridges
Rotational stiffness is a crucial element in engineering structures, especially in the construction of skyscrapers and bridges. One of the factors in engineering is that the structure must be able to support loads without twisting.