Light Truck Frame Joint Stiffness Study Phase 1 Final Report

LITERATURE SEARCH
Introduction
A literature search was performed to identify previous published papers on testing, finite element analysis
and design guidelines for steel joints. The research is summarized below. Abstracts of the 43 articles that
we identified as relevant and read, along with 12 additional articles that we judged not relevant and did
not pursue, are included in the appendix.
Two papers contained information on light truck frames and frame stiffness. The articles were written on a
van frame structural evaluation (Hull, 1979) and an idealized truck frame design (Michejda, 1971). Both
articles mentioned joint stiffness but provided very little detailed information about joint design or analysis.
Much of the available automotive research focused on body joint design. There were many papers on
welded joints used in construction trusses and offshore oil platforms (tube through tube joints) which
provided valuable information on joint measurement and test fixtures.
Defining the Joint
Studies from civil engineering structures focused extensively on structural (non-automotive) frames and
joint stiffness and stress testing. These studies, however, included pertinent information regarding
specimen size, constraints, loading and instrumentation. The length of the structure surrounding the joint
interface should be sufficiently long to minimize the influence of the end conditions (Chiew, 1996), and
sufficiently small to keep the surrounding structure from affecting the stiffness. The joint dimensions we
used were based on the work of Rao et. al. 1983 and adhered to the following guidelines:
• The test joints contained a finite amount of surrounding structure
• All unique characteristics of the joints were included (i.e. local reinforcements, extended flanges,
access and lighting holes)
• Inclusion of surrounding structure was minimized to prevent joint stiffness value contamination
• Standard dimensions containing identical amounts of structure were used, when possible, for
comparison across joint types
• Joint samples were removed from the frame structure to isolate their performance. To facilitate
testing, joint boundaries were developed in the plane of the cross section of the crossmember and rail
• Load and support plates were welded to the ends of the joint specimen for load application and
restraint
Our test samples adhered to the guidelines in the following manner:
• Joints were tested to evaluate the optimum length to incorporate the unique characteristics of the joint
• We established boundaries 150mm from the joint interface to be used in all joint samples
• The joints were removed from the surrounding frame structure at the established boundaries
• ¾-inch end plates were welded to the joint for the constraining and load application fixture
Report: A/SP-005-1 Light Truck Frame Joint Stiffness Study 6