Improvement of actuation displacement of LIPCA implementing bifurcation phenomena

Abstract

In this work, behavior of a unimorph piezoceramic actuator, LIPCA (Lightweight Piezo-Composite Actuator) under compression has been experimentally and numerically investigated. The LIPCA composed of composite laminated tabs, piezoceramic material layer, glass/epoxy composite and carbon fiber composite layers was modeled and analyzed by using a full three-dimensional finite element modeling technique. The geometrically nonlinear analysis was used in the analysis because the LIPCA has the initial curvature due to the curing process, which acts like an initial geometric imperfection. The LIPCA was installed in the simply supported configuration and compressive load was applied in the test jig. By measuring the lateral displacement created by the compressive load, the buckling load of the LIPCA was determined. The measured buckling load agreed well with the computed linear buckling load from the finite element analysis based on the thermal analogy. As various electric fields were applied to the LIPCA under the compressive load, the lateral displacement was measured to examine behavior of the LIPCA under the compressive load and electric field at the same time. From this test, proper combinations of the compressive load and prescribed voltage could be figured out, which can create controlled buckling of the LIPCA under compression by applying the electric field. The measured data showed that the lateral displacement of the LIPCA is significantly increased when a proper electric field is prescribed to the LIPCA in addition to the pre-determined compressive load. The measured data was compared with the computed result from the geometrically nonlinear finite element analysis based on the thermal analogy. The numerical simulation agreed well with the measurement for low compressive load (< 3N) and low electric field (< 150V). The strength of the LIPCA is also calculated to make sure that the actuator can be operated without fracture.