A method for producing a partly transparent body with a color gradient, include: providing a transparent first casing having a first joint surface on a protrusion and including an encased object; providing a second casing which is not completely transparent and which has a second joint surface in a recess. The shape of the protrusion and the shape of the recess correspond to each other; and combining the first casing and the second casing by inserting the protrusion into the recess and melting the first joint surface of the first casing with the second joint surface of the second casing. A pressure force and a temperature are applied to the first joint surface and the second joint surface such that the first joint surface of the first casing transitions into the second joint surface of the second casing in a visually seamless manner, followed by a removal of material.

According to one implementation, a composite material structure includes a first member and a second member. The first member has at least one first bonded surface. The second member has at least one second bonded surface to be bonded to the at least one first bonded surface. The second member is made of a composite material. At least one surface formed by fibers forming the composite material is used as the at least one second bonded surface by disposing end portions of the fibers, in the first member side, inside the composite material.

A curved composite structure, comprises at least two curved composite panel segments joined together. Each of the panel segments includes a fluted core sandwiched between first and second facesheets. A layer of adhesive is used to rigidly bond the panel segments together.

A frictional weld joint couples together first and second body portions of an article. The first body portion has a first nominal wall thickness and a first joint surface. The second body portion has a second nominal wall thickness and a second joint surface. A total bead height is defined between the joint surfaces. A first bead extends from the first joint surface defining a first bead height. A second bead extends from the second joint surface and is coupled to the first bead. A final second bead height is defined between the first bead and the second joint surface. A ratio of the first bead height to the final second bead height is of from about 0.40 to about 1.70. A ratio of the total bead height to at least one of the first and second nominal wall thicknesses is equal to or less than 6.00.

A waveguide for plastic welding has an entry end, an exit end as well as a first and a second inner face arranged between the entry end and the exit end, which are arranged opposite to each other and by means of which laser light can be reflected. A first distance between the entry end and the exit end defines a length of the waveguide and a second distance between the first and the second inner face defines a thickness of the waveguide. The exit end may be arranged opposite to the entry end and a central plane of the waveguide may extend centrally from the entry end to the exit end. The first inner face comprises a continuously curved, concave shape so that a third distance between the first inner face and the central plane varies continuously from the entry end in the direction of the exit end.