The pilot reported that 15 minutes after takeoff, during cruise flight, the engine experienced a total loss of power. She pulled the carburetor heat control knob on, and initiated a forced landing to a grassy field. During the landing roll, the airplane collided with heavy vegetation, which resulted in substantial damage to the left wing. About 30 minutes prior to the accident, a weather station located about 10 nautical miles from the accident site reported a temperature of 48 degrees F and dew point of 43 degrees F. These weather conditions were conductive to the high probability of carburetor ice formation, with the potential for serious icing at cruise power. During the postaccident engine examination, the engine was prepared for an engine run. The engine was started and run with no mechanical failures or malfunctions noted that would have precluded normal operation.