In recent years, the usage of extremely powerful explosive devices in military operations and in terrorist attacks on civilian targets has become the hallmark of modern warfare and an increasing threat to both civilian and military personnel 
. Blast injuries, as the result of physical trauma sustained in combat or terrorist explosions, are increasingly recognized and encountered worldwide. Explosive blast creates a defining supersonic over-pressurization shock wave 
. A blast shock wave is a high-pressure area that expands rapidly outward from an explosive center as a sphere of compressed gases. It is characterized with a leading shock front of increased positive air pressure (which mainly causes damage at a distance from the explosion center) and a blast wind of negative air pressure (which follows immediately after the positive air pressure and sucks items back in towards the explosion center). Blast shock wave carries energy (an overpressure of 60–80 PSI) and can propagate at very high speeds (approximately 3,000–8,000 m/sec). The energy of a blast shock wave dissipates relatively quickly with distance 
. When a blast shock wave interacts with a medium (solid, liquid, gas or plasma), the energy can be absorbed or transformed to kinetic energy of the medium that accelerates a body of a given mass from rest to its stated velocity. It initiates a retardation and energy absorbing process that captures the blast shock wave, and results in the rapid physical movement, displacement, deformation or breakage of the medium 
Personal protection against blast shock wave is currently the most difficult challenges facing body armor researchers and engineers. The rapid impact (compression) effects of blast shock wave on the human body may be the reason why fielded body armor and helmets can successfully prevent penetrating ballistic and stab injuries, but fail to mitigate against primary blast injuries caused by a blast shock wave. When blast shock wave acts on a soldier wearing currently standard fielded body armor, the personal armor is forced by surrounding overpressure to move rapidly toward the human body. The rapid impact of armors on the body, results in the non-penetrating injury, “Behind Armour Blunt Trauma” (BABT) 
. Therefore, currently fielded body armor may not be able to protect the body against the impact of blast shock wave. In contrast, it can be possibly involved in coordination efforts with blast shock wave to increase the impact force to the body, causing more serious bodily injuries. Clearly, what is required to prevent and mitigate the primary blast injuries is an innovative body armor, which can protect effectively against the impact of blast shock wave.
In this study, the hydraulic energy redirection and release technology that aims to mitigate the impact of blast shock wave on the protected objects was developed based on the propagation and energy transfer characteristics of blast shock wave in a liquid 
. Hydraulic energy is the power created by the compressive force or movement of a liquid in a confined area or a piping system. The power can be transferred and distributed through small tubes and flexible hoses, and be appropriately used for different machinery and tools such as hydraulic presses, hydraulic metal cutting machines, hydraulic excavators, and hydraulic forklift trucks. The hydraulic energy redirection and release technology employs the liquid-filled plastic tubings (which are similar to blood vessels filled with blood) as a blast pressure transformer to transfer kinetic energy of blast shock waves into hydraulic energy and to redirect and distribute hydraulic energy to the lower end of the liquid-filled piping system. This may cause blast overpressure to be released from the outer surface of the body armor or blast shelter through the openings at the lower end of the liquid-filled piping system without suffering damage to the human body. To evaluate the effectiveness of the hydraulic energy redirection and release technology on blast shock wave mitigation, the samples of the specifically designed blast-resistant body armor that were installed with the water-filled plastic tubings were tested.