fluent内置的流固耦合，fluent设置结构为线性弹性时报错？

想做fluent内置的流固耦合，网格是用fluent自带的网格划分做的，然后fluent设置结构为线性弹性时报错，报错信息为：The Structural Model has the following incompatibilites: Polyhedral solid elements are not supported.Disabling Structural Model due to model incompatibilities.有人知道是为什么嘛