Energy shields are pretty common things in fiction, with some being nebulous things that cloak you in a protective shield that absorbs damage that could otherwise harm the user, and others being literal shields from medieval times, but energy based instead.
What I would like to address here is the practical considerations that would come into play regarding surrounding yourself with an energy based force-field.
I think that some of the Halo lore regarding Spartan shields seems like it comes the closest to making a reasonable level of sense. For those that are not familiar: the shield acts like a sort of frictionless surface, that would cause the soldier to otherwise slide around or be unable to properly interact with objects or the environment if the shields were not 'tuned' to be weaker around the hands and feet. Which then raises the interesting question to me, if I were to tightly close my fist, would that not drain resources from the shield? Or If I were to high-five someone, would that not also have the same effect? An additional consideration is that the shields of the universe are impermeable, as covenant ships needed to lower a section of shield to actually fire out of them. So in summation, we have an energy shield that acts like a solid.
I'm using a similar type of technology in one of my stories. A super soldier in powered armor, cloaked in a protective shield of energy. This soldier will encounter human enemies as well as creatures. The question here is, does it make sense for the super soldier to punch an enemy with his shields up? Would it be sort of the trope of head-butting someone, where "nobody wins", and drain the shields tremendously, or would it have a fairly negligible effect?
I recognize that this by itself is not a sufficiently concrete question, so let me define a few things so we can drill down and perhaps reach a more definitive answer.
- Through augmentations as well as the strength granted by the power suit, is able to bend steel prison style bars, and can flip the equivalent of an ambulance or fire truck (with effort).
- Can take a 30 round magazine of .308 bullets before failing.
- The shield is very energy efficient when it is maintained at full strength, and can remain operational for days or weeks before a battery recharge becomes necessary, but can only refill the strength of the shield 10-20 times from combat before needing a battery recharge.
- The user of the shield is entirely unaffected by any attack. An example: if a medieval knight was slapped, he wouldn't feel pain due to helmet and padding, but his head would be moved by the recoil. In this case, the soldier doesn't even experience the recoil as the shield completely takes it.
- It is physically impossible to 'defeat' an acute section of the shield and bypass it: it must totally fail for the user to be affected.
So with all this in mind, if the soldier needed to put his full strength into striking a creature, does it make sense for him to attack with the shields up, or should he lower them around his hands to preserve their strength, and make himself vulnerable as well as put wear and tear on the suit?
Addendum: The minutiae of how the shield technology works, etc, are obviously subjective, and greatly affect the cost benefit analysis of whether hand to hand combat in this case would make sense. However, the objective question here is revolving around the kinetic energy of said punch/kick or strike and how it compares to the kinetic energy of the 30 rounds of .308.