Adds a custom tab to WooCommerce this one is for downloads but it can be for anything if the tab file is set up correctly,
add_filter( 'woocommerce_product_tabs', 'sb_woo_new_test_tab');
function sb_woo_downloads_tab_content() {
woocommerce_get_template( 'single-product/tabs/downloads.php' );
}
function sb_woo_new_test_tab($tabs) {
$tabs['test_tab'] = array(
'title' => __( 'Data Sheets', 'woocommerce' ),
'priority' => 50,
'callback' => 'sb_woo_downloads_tab_content'
);
return $tabs;
}