In this study, the static and dynamic behaviors under different environmental conditions of mechanical insert butt joints with butterfly joint locks that could be used instead of adhesively bonded butt joints in composite plate joints were investigated. The experimental specimens and butterfly-shaped joining components with the same material configuration were cut from a [(0/90)8]s laminated composite plate with a water jet in harmony with the geometric parameters. The fatigue experiments were carried out at a constant load ratio of 0.1 and at different maximum fatigue loads. To compare the joints with each other, the experiments were conducted under a 10-Hz fatigue frequency and under a tensiontension load with constant amplitude of a sinus curve shape. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013