\documentclass{article}
\usepackage{array}
\makeatletter
\def\hlinewd#1{%
\noalign{\ifnum0=`}\fi\hrule \@height #1 \futurelet
\reserved@a\@xhline}
\makeatother
\begin{document}
\begin{tabular}{|c|c!{\vrule width 1pt}c||c|} \hlinewd{3pt}
Model & $E_k / E_p$ & Non-dim. & Ratio. \\ \hlinewd{3pt}
A1 & 3.62 & 20.12 & 0.912 \\ \hline
A5 & 7.10 & 22.75 & 1.139 \\ \hlinewd{3pt}
\end{tabular}
\end{document}