A washer assembly is configured to isolate a work-piece from a fastener and/or another structure. The washer assembly includes a rubber isolator having at least one protuberance configured to directly contact a surface of the work-piece, and a metal strengthening member permanently secured to the rubber isolator. The protuberance(s) is configured to be compressed during a normal operating condition. The metal strengthening member is configured to be compressed during a peak operating condition in which greater force is exerted into the washer assembly than during the normal operating condition.