@classmethod
def export_to_hdf5(cls, h5_file, model, mids):
    """exports the elements in a vectorized way"""
    comments = []
    G = []
    rho = []
    a = []
    tref = []
    ge = []
    for mid in mids:
        material = model.materials[mid]
        G.append(material.D())
        rho.append(material.rho)
        a.append(material.A)
        tref.append(material.tref)
        ge.append(material.ge)
    h5_file.create_dataset('mid', data=mids)
    h5_file.create_dataset('G', data=G)
    h5_file.create_dataset('A', data=a)
    h5_file.create_dataset('rho', data=rho)
    h5_file.create_dataset('tref', data=tref)
    h5_file.create_dataset('ge', data=ge)
