a first object is anchored in a second object . the first object has a material with thermoplastic properties , and the second material has a material that is solid and is penetrable by the first material when in a liquefied state . the second object has an insertion face with an opening having a mouth in the insertion face , and the first object has an insert portion that for anchoring is placed in the opening or about the mouth thereof . for anchoring , energy suitable for liquefaction of the first material impinges in an amount and for a time sufficient for at least partial liquefaction of the first material and interpenetration of the first and second materials . the second object , around the opening , has an anisotropic strength with respect to forces perpendicular to the opening axis .