industry news, news 05/08/2026 2
The connection structure for zig zag wire featuring straight extensions at both ends is a critical design element that ensures secure load transfer from the flexible wave section to a rigid support frame. This configuration transforms the wire from a standalone component into an integrated structural member.
The straight extension, or terminal, is designed as a transitional structural element. Its primary function is to provide a robust, flat, and stable interface for connection. The length of this straight section is calculated based on the connection method. For bolted connections, the length must accommodate the bolt hole diameter while maintaining a minimum edge distance—typically 1.5 to 2 times the bolt diameter—to prevent tear-out under load. The design also specifies a standard hole diameter with a slight clearance (e.g., 0.5mm to 1mm larger than the bolt) to account for minor assembly misalignments without compromising shear strength.
The cross-section of the terminal is often modified from the original round wire. A common practice is to forge or cold-form the last portion of the straight extension into a flattened paddle or to create a specific profile like a hook or a loop. This flattening increases the bearing surface area against the mounting bracket, reducing contact pressure and improving clamp load distribution. The transition from the round wire to the flattened terminal is engineered with a generous radius to avoid a sharp stress concentrator. For high-load applications, the terminal may be upset-forged to create a larger diameter head, providing more material around the bolt hole and significantly increasing pull-through resistance.
For welded assemblies, the terminal design prioritizes weld land preparation. The straight extension may be beveled at the end to allow for a full-penetration groove weld. Alternatively, the sides of a flattened terminal can be used for robust fillet welds. The design specifies the weld type, leg size, and length based on the wire’s ultimate tensile strength and the required safety factor. The straight, un-crimped nature of the extension ensures consistent, high-quality weld joints by providing a stable, easy-to-fixture surface that is free from the springback forces present in the wave section.
The fundamental engineering challenge is managing the transition of forces from the dynamic, oscillating wave section to the static, fixed connection point. A poorly designed transition creates a stress hotspot, leading to fatigue failure. The connection structure addresses this by ensuring load path continuity. The straight extension acts as a moment arm. When the wave section is loaded, the forces are resolved into axial, shear, and moment components at the base of the first wave. The straight extension transmits these forces to the connection hardware. The design ensures that the centroidal axis of the wave section aligns as closely as possible with the centroid of the connection (e.g., the center of a bolt hole). This minimizes eccentric loading that would induce a prying action on the bolt or create a bending moment in the terminal itself.
The transition zone—where the last wave meets the straight extension—is a focal point of the design. This area is often reinforced. One method is to locally increase the wire diameter through swaging or upsetting just before the straight section begins. Another is to design the final wave with a modified, gentler radius to reduce the bending stress at that specific location. Finite Element Analysis (FEA) is used to model this transition under operational loads, identifying high-stress areas. The design is then iterated, potentially adding material or smoothing the geometry, until the stress concentration factor is minimized and the stress flow appears smooth and continuous in the simulation.
For applications involving thermal cycling or significant differential expansion between the wire and its support structure, the connection must accommodate movement without inducing excessive stress. A slotted hole in the terminal, aligned with the direction of expected thermal movement, is a common solution. This allows the bolt to slide within the slot, preventing the build-up of thermal stress in the wire while still restraining it in other directions. The length of the slot is calculated based on the coefficient of thermal expansion, the temperature range, and the distance between fixed connection points.
The connection structure is designed for efficient and reliable assembly. For bolted connections, the straight extensions on both ends ensure parallel mounting surfaces. This allows the wire to be dropped into place between two pre-drilled brackets and secured with a single bolt at each end, simplifying installation. The design may incorporate self-locating features, such as a pilot dimple or a small tab on the terminal that fits into a corresponding slot on the bracket, ensuring correct alignment before the bolts are tightened.
Vibration resistance is a critical requirement in many industrial settings. To prevent bolted connections from loosening over time, the design integrates positive locking features. This can include a pre-applied thread-locking adhesive on the bolt, the use of serrated flange nuts, or the design of the terminal itself. For instance, the flattened terminal surface may be knurled or stamped with a radial serration pattern. When the nut is torqued down, these serrations bite into the mounting bracket, creating a vibration-resistant, non-slip interface. For permanent installations, the design may specify a prevailing-torque locknut or a deformed thread nut that provides consistent locking force.
In modular or panelized systems, the connection structure enables rapid interconnection. The straight extension on one wire may be designed with a hook or a clevis, while the extension on the adjacent wire has a corresponding hole or pin. This allows wires to be linked together in the field without additional hardware, creating larger assemblies from standard components. The geometry of these inter-wire connections is designed to carry shear loads while allowing a degree of rotational freedom, accommodating slight misalignments and distributing loads across multiple wires in the assembly, thereby creating a robust and adaptable structural network from individual zig zag wire elements.