INSULATING of automobile bodies against noise and heat has been made more complicated by the trend toward lower and more compact bodies and larger and more powerful engines, as more noise and heat are created and must be excluded from the body. Development of the all-steel body also has presented a new problem that calls for different treatment than the composite steel and wood body.
Elimination of noise and heat from the body is the mutual problem of the chassis and the body engineers and must be attacked jointly, correction of the trouble being made at the most logical and practical places. Much successful work has been done in the last few years to eliminate noise and heat, but much more can be accomplished by further concentrated effort.
After listing the more objectionable chassis noises which have received most attention, the author considers the remaining noise and the heat against which the body must be insulated. He then proceeds to a consideration of available insulating materials and adhesives that are suitable for the purpose, describes testing methods and gives details of application to and treatment of different parts of the body.
In conclusion, probable future developments in body insulation are forecast.
A discusser mentions the direct application of acoustical knowledge to treatment of the problem, saying that engine vibrations are transmitted to the chassis frame and are amplified by vibration of the body panels at frequencies of the same order as the primary vibrations from the power source or driving force and that low frequencies are the more difficult to control. In reply, the author states his belief that low-frequency vibration is the most desirable and that reducing the period of the panels below the range of frequency of the frame is not necessary.