A cycloolefin polymer (COP) bonding method wherein a first material that is COP and a second material that is COP or glass are bonded. The method includes: a step of exposing at least a bonding surface of the first material to H.sub.2O plasma; and a step of mating the bonding surface of the first material and a bonding surface of the second material. According to the method, the cycloolefin polymer (COP) can be bonded to a target material without applying high pressure or high temperature, and without affecting the optical properties.

A method for optimizing a welding process to produce a weld joint having a predetermined strength includes measuring a plurality of melt layer thicknesses of weld joints for a plurality of sample assemblies formed by the welding process, measuring a plurality failure loads of weld joints for the plurality of sample assemblies, each of the measured plurality of failures loads being associated with one of the measured plurality of melt layer thicknesses, selecting a first failure load from the plurality of measured failure loads responsive to determining that the first failure load corresponds to a predetermined weld strength, and selecting a first melt layer thickness from the plurality of measured melt layer thicknesses that is associated with the selected first measured failure load.

According to one aspect of the present invention, there is provided a hollow structure body having a hollow structure, in which a first shaped product constituted by a first fiber-reinforced resin material containing first reinforcing fibers and a first matrix resin and a second shaped product constituted by a second fiber-reinforced resin material containing second reinforcing fibers and a second matrix resin are combined, wherein in an arbitrary cross section in a direction perpendicular to an axial direction of the hollow structure, a ratio Sc/St between compressive strength Sc of a structure in the first shaped product and tensile strength St of a structure in the second shaped product satisfies formula (1):
(σc/σt)*(Hc/Ht)<(Sc/St)<(σt/σc)*(Hc/Ht)  formula (1).

What is provided is a new and improved metal-carbon fiber reinforced resin material composite in which the galvanic corrosion of dissimilar materials of a metal member is suppressed and electrodeposition coatability is excellent and a method for manufacturing the metal-carbon fiber reinforced resin material composite. A metal-carbon fiber reinforced resin material composite according to the present invention has a metal member, a resin coating layer disposed on at least a part of a surface of the metal member, and a carbon fiber reinforced resin material containing a matrix resin and a carbon fiber material present in the matrix resin, the resin coating layer contains any one or more kinds selected from the group consisting of metal particles, intermetallic compound particles, conductive oxide particles, and conductive non-oxide ceramic particles as conductive particles and further contains a binder resin, and the conductive particles have a powder resistivity at 23° C. to 27° C. of 7.0×10.sup.7 Ω.Math.cm or less and contain one or more selected from the group consisting of Zn, Si, Zr, V, Cr, Mo, Mn, and W.

A method for optimizing a welding process to produce a weld joint having a predetermined strength includes measuring a plurality of melt layer thicknesses of weld joints for a plurality of sample assemblies formed by the welding process, measuring a plurality failure loads of weld joints for the plurality of sample assemblies, each of the measured plurality of failures loads being associated with one of the measured plurality of melt layer thicknesses, selecting a first failure load from the plurality of measured failure loads responsive to determining that the first failure load corresponds to a predetermined weld strength, and selecting a first melt layer thickness from the plurality of measured melt layer thicknesses that is associated with the selected first measured failure load.

A method for optimizing a welding process to produce a weld joint having a predetermined strength includes measuring a plurality of melt layer thicknesses of weld joints for a plurality of sample assemblies formed by the welding process, measuring a plurality failure loads of weld joints for the plurality of sample assemblies, each of the measured plurality of failures loads being associated with one of the measured plurality of melt layer thicknesses, selecting a first failure load from the plurality of measured failure loads responsive to determining that the first failure load corresponds to a predetermined weld strength, and selecting a first melt layer thickness from the plurality of measured melt layer thicknesses that is associated with the selected first measured failure load.

A cycloolefin polymer (COP) bonding method wherein a first material that is COP and a second material that is COP or glass are bonded. The method includes: a step of exposing at least a bonding surface of the first material to H.sub.2O plasma; and a step of mating the bonding surface of the first material and a bonding surface of the second material. According to the method, the cycloolefin polymer (COP) can be bonded to a target material without applying high pressure or high temperature, and without affecting the optical properties.

A method for optimizing a welding process to produce a weld joint having a predetermined strength includes measuring a plurality of melt layer thicknesses of weld joints for a plurality of sample assemblies formed by the welding process, measuring a plurality failure loads of weld joints for the plurality of sample assemblies, each of the measured plurality of failures loads being associated with one of the measured plurality of melt layer thicknesses, selecting a first failure load from the plurality of measured failure loads responsive to determining that the first failure load corresponds to a predetermined weld strength, and selecting a first melt layer thickness from the plurality of measured melt layer thicknesses that is associated with the selected first measured failure load.

A fusion bead testing device is provided for testing the strength of a fusion bead removed from a pipe joint. The testing device comprises a first pressing means for exerting a force against the fusion bead. If the fusion bead splits as a result of the applied force then the fusion bead fails a quality control test and the fusion bead and consequently the pipe joint from which the bead was removed are deemed too weak. The fusion bead testing apparatus comprises an automatic split detection device for detecting a split in the bead.

A fiber reinforced composite material structure comprises a thin sheet that includes a first surface and a plurality of convex portions which protrude and are regularly arranged on the first surface and each of which includes a top face; and a surface material that includes a second surface and is bonded to the top faces on the second surface.