private void setInnerBound()
        {
            centroid = MeshTools.meshCentroid(boundary);
            Mesh offset = MeshTools.makeCuboid(cellPlane, xDim - memberSize, yDim - memberSize, zDim - memberSize);

            innerBoundary = Brep.CreateFromMesh(offset, false);

            foreach (BrepVertex p in innerBoundary.Vertices)
            {
                nodeGrid.Add(p.Location);
            }
            nodeGrid.Add(new Line(nodeGrid[0], nodeGrid[2]).PointAt(0.5));
            nodeGrid.Add(new Line(nodeGrid[1], nodeGrid[3]).PointAt(0.5));
            nodeGrid.Add(new Line(nodeGrid[6], nodeGrid[4]).PointAt(0.5));
            nodeGrid.Add(new Line(nodeGrid[7], nodeGrid[5]).PointAt(0.5));

            setCentreLines();
            //foreach(BrepEdge be in innerBoundary.Edges)
            //{
            //    untrimmedCentreLines.Add(be.DuplicateCurve());
            //}
            ////add diagonals

            for (int d = 0; d < 11; d++)
            {
                diagonalMembers.Add(new DiagonalMember(d, nodeGrid));
            }
            //set the faceboundaries
            setBoundaryGeometry();
        }