\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}