Make that overlap length as long as possible…the longer the better I always say…we don’t want the bonded joint to fail…says the confident designer with an unfettered surety…hmmm...well, not quite.
Longer is not necessarily better in this case. So, for those of you interested in approximating the performance of an adhesively bonded joint “quickly” while adhering to a few basic engineering principles that will establish optimal joint parameters, then perhaps you may want to take a look at one of the simplest closed-form methods available. In 1938, the Volkersen’s Method, also known as the “shear-lag model”, was first used for mechanical joints with fasteners. Invariably, this method was used to assess failure in adhesively bonded lap joints. Of course, the method is not without some underlying assumptions which limit its use, but I will be address those later.