Abstract: The invention provides composite components, structures and method for producing composite components A composite component has a negative effective Poisson's ratio and comprises a first component and a second component. The first component and the second component extend longitudinally relative to an axis, the first component being provided around the second component through one or more turns which are spaced longitudinally relative to the axis. A variation in the tensile load on the first component causes the radial position of the second component relative to the axis to vary.