Hollow Sections—How to Make Composite Tubes

Abstract

This chapter considers the manufacture of hollow sections. Mandrel lamination (wrapping) and bladder moulding are described and then used to create composite tubes. A step-by-step guide to tube manufacture is presented for prepreg moulding, but the fabrication methods introduced are more widely applicable (and hence, can be adapted for use in wet layup processes). Whilst the focus is on cylindrical tubes, the fabrication process can be simply modified to create square or rectangular hollow sections or more complex tubular structures. A helical spring and a bicycle handlebar are used as more complex examples. Demoulding methods for mandrel wrapped tubes are discussed. A specific focus is given to mechanical extraction and thermal (heating and cooling) mechanisms. The concept of mouldless composite construction is introduced. The importance of a mandrel’s coefficient of thermal expansion is considered in the context of demoulding using thermal methods.