Constance Tipper, a metallurgist whose test for determining the brittleness of steel kept Britain’s Liberty ships afloat in World War II, has died. She was 101.

Tipper died Dec. 14 at her home in the northwest England town of Penrit.

She was a researcher at Cambridge University in World War II when Britain began looking for an explanation of why some of its Liberty merchant vessels cracked like glass at sea.

British military authorities blamed engineering design or welding, but Tipper said the problem was with the steel. She developed what is now known as the “Tipper Test” to determine the brittleness of the metal.

Tipper was virtually the only woman working in the field at the time.