A generator has been designed to generate simulating underpressure of blast wave and applied for the study of underpressure injuries on animals.The generator is composed of a vacuum pump,a hypotcnsive chamber,an experimental chamber,a membrane-rupturing device and a pressure-measuring system.Its operating principle is as follows:When the pressure of the hypotensive chamber is being decreased by the drawing of the vacuum pump to a given level .the membrane separating the hypotensive chamber and the experimental chamber is rapidly perforated by a sharp pointer.Underpressure occurs in the experimental chamber where the animal is fixed as soon as the pressure changes instantaneously.The range of the physical parameters of the simulated underpressure are -13 to -90 kPa for the peak level,1 ms to 90 ms for the decreasing time,and 14 ms to 2000 ms for the duration.Animal experimentation revealed that this device is capable of inflicting injuries and verified the possibility that the underpressure of blast waves can result in injuries.

Objective To design and produce serial shock tubes and further examine their application to experimental studies on blast injury.Methods Bio-medical engineering technique was used for the design and development of the serial shock tubes. One thousand four hundred and fifty nine animals (757 rats, 105 guinea pigs, 335 rabbits, 240 dogs and 22 sheep) were then used to test the wounding effects of the shock tubes.Results Three types of bio-shock tubes, that is, large-, medium- and small-scale shock tubes were made in our laboratory. The large-scale shock tube is 39 meters long; the inner diameter of the test section is 1 meter; and the maximum overpressure in the driving section is 10.3 MPa. A negative pressure could be formed by means of the reflected rarefactive wave produced by the end plate. The medium-scale shock tube is 34.5 meters long; the maximum overpressure in the driving section is 22 MPa; the test section is designed to be a knockdown, showing 5 basic types with inner diameter of 77 to 600 millimeters, which could be used for researches on overpressure, explosive decompression, underwater explosion, and so on. The small-scale shock tube is 0.5 meter long with the maximum endured overpressure of 68.6 MPa. Results from animal experiments showed that this set of shock tubes could induce various degrees of systemic or local blast injury in large or small animals. Conclusions This set of bio-shock tubes can approximately simulate typical explosive wave produced by nuclear or charge explosion, and inflict various degrees of blast injury characterized by stability and reproducibility. Therefore, they can meet the needs of blast research on large and small animals.